diff --git a/behat.yml b/behat.yml
index 5bf5117e..96670f81 100644
--- a/behat.yml
+++ b/behat.yml
@@ -17,7 +17,7 @@ default:
         - SilverStripe\BehatExtension\Context\LoginContext
         -
           DNADesign\Elemental\Tests\Behat\Context\FixtureContext:
-            - '%paths.modules.silverstripe-elemental%/tests/Behat'
+            - '%paths.modules.silverstripe-elemental%/tests/Behat/files'
         -
           SilverStripe\Framework\Tests\Behaviour\ConfigContext:
             - '%paths.modules.silverstripe-elemental%/tests/Behat/config'
diff --git a/tests/Behat/Context/FixtureContext.php b/tests/Behat/Context/FixtureContext.php
index 564434bd..4b2ced91 100644
--- a/tests/Behat/Context/FixtureContext.php
+++ b/tests/Behat/Context/FixtureContext.php
@@ -4,6 +4,7 @@
 use DNADesign\Elemental\Models\BaseElement;
 use DNADesign\Elemental\Models\ElementalArea;
 use DNADesign\Elemental\Models\ElementContent;
+use PHPUnit\Framework\Assert;
 use SilverStripe\CMS\Tests\Behaviour\FixtureContext as BaseFixtureContext;
 use SilverStripe\Core\ClassInfo;
 use SilverStripe\ORM\DB;
@@ -111,4 +112,55 @@ protected function getElementalArea(string $type, string $pageTitle): ElementalA
 
         return $page->ElementalArea();
     }
+
+    /**
+     * The method is copied from asset-admin SilverStripe\AssetAdmin\Tests\Behat\Context\FixtureContext
+     * Behat does not seem to allow two different FixtureContext files to be added in the
+     * same behat.yml config file
+     *
+     * Select a gallery item by type and name
+     *
+     * @Given /^I (?:(?:click on)|(?:select)) the (?:file|folder) named "([^"]+)" in the gallery$/
+     * @param string $name
+     */
+    public function stepISelectGalleryItem($name)
+    {
+        $item = $this->getGalleryItem($name);
+        Assert::assertNotNull($item, "File named $name could not be found");
+        $item->click();
+    }
+
+    /**
+     * The method is copied from asset-admin SilverStripe\AssetAdmin\Tests\Behat\Context\FixtureContext
+     * Behat does not seem to allow two different FixtureContext files to be added in the
+     * same behat.yml config file
+     *
+     * Helper for finding items in the visible gallery view
+     *
+     * @param string $name Title of item
+     * @param int $timeout
+     * @return NodeElement
+     */
+    protected function getGalleryItem($name, $timeout = 3)
+    {
+        /** @var DocumentElement $page */
+        $page = $this->getMainContext()->getSession()->getPage();
+        // Find by cell
+        $cell = $page->find(
+            'xpath',
+            "//div[contains(@class, 'gallery-item')]//div[contains(text(), '{$name}')]"
+        );
+        if ($cell) {
+            return $cell;
+        }
+        // Find by row
+        $row = $page->find(
+            'xpath',
+            "//tr[contains(@class, 'gallery__table-row')]//div[contains(text(), '{$name}')]"
+        );
+        if ($row) {
+            return $row;
+        }
+        return null;
+    }
 }
diff --git a/tests/Behat/features/inline-block-validation.feature b/tests/Behat/features/inline-block-validation.feature
index 63f4d71a..9eed13a8 100644
--- a/tests/Behat/features/inline-block-validation.feature
+++ b/tests/Behat/features/inline-block-validation.feature
@@ -8,6 +8,7 @@ Feature: Blocks are validated when inline saving individual blocks
     Given I add an extension "DNADesign\Elemental\Extensions\ElementalPageExtension" to the "Page" class
     And I add an extension "SilverStripe\FrameworkTest\Elemental\Extension\ElementContentExtension" to the "DNADesign\Elemental\Models\ElementContent" class
     And I add an extension "SilverStripe\FrameworkTest\Elemental\Extension\NumericFieldExtension" to the "SilverStripe\Forms\NumericField" class
+    And a "image" "file1.jpg"
     And I go to "/dev/build?flush"
     And a "page" "Blocks Page" with a "My title" content element with "My content" content
     And the "group" "EDITOR" has permissions "Access to 'Pages' section"
@@ -17,6 +18,10 @@ Feature: Blocks are validated when inline saving individual blocks
     And I click on the caret button for block 1
     And I click on the "#Form_ElementForm_1_PageElements_1_MyPageID" element
     And I click on the ".ss-searchable-dropdown-field__option:nth-of-type(2)" element
+    And I click "Choose existing" in the ".uploadfield" element
+    And I press the "Back" HTML field button
+    And I click on the file named "file1" in the gallery
+    And I press the "Insert" button
     And I press the "View actions" button
     And I click on the ".element-editor__actions-save" element
 
@@ -31,7 +36,6 @@ Feature: Blocks are validated when inline saving individual blocks
     # Will not be an inline save button because formDirty not set yet, intercepted by JS validation
     Then I should not see a ".element-editor__actions-save" element
 
-@sboyd
   Scenario: Field validation error
     When I fill in "x" for "Title" for block 1
     When I press the "View actions" button
@@ -57,6 +61,30 @@ Feature: Blocks are validated when inline saving individual blocks
     # Need to save the whole page to stop the alert
     And I press the "Save" button
 
+  Scenario: Related data validation error with ID suffix (MyPageID)
+    When I click on the "#Form_ElementForm_1_PageElements_1_MyPageID" element
+    And I click on the ".ss-searchable-dropdown-field__option:nth-of-type(1)" element
+    And I press the "View actions" button
+    And I click on the ".element-editor__actions-save" element
+    Then I should see "\"My page\" is required" in the ".form__validation-message" element
+    When I click on the "#Form_ElementForm_1_PageElements_1_MyPageID" element
+    And I click on the ".ss-searchable-dropdown-field__option:nth-of-type(2)" element
+    And I press the "View actions" button
+    And I click on the ".element-editor__actions-save" element
+    Then I should see a "Saved 'My title' successfully" success toast
+
+  Scenario: Related data validation error without ID suffix (MyFile)
+    When I click on the ".uploadfield-item__remove-btn" element
+    And I press the "View actions" button
+    And I click on the ".element-editor__actions-save" element
+    Then I should see "\"My File\" is required" in the ".form__validation-message" element
+    When I click "Choose existing" in the ".uploadfield" element
+    And I click on the file named "file1" in the gallery
+    And I press the "Insert" button
+    And I press the "View actions" button
+    And I click on the ".element-editor__actions-save" element
+    Then I should see a "Saved 'My title' successfully" success toast
+
   Scenario: Publishing triggers validation error
     When I fill in "x" for "Title" for block 1
     When I press the "View actions" button
diff --git a/tests/Behat/features/non-inline-block-validation.feature b/tests/Behat/features/non-inline-block-validation.feature
index 48eb7d07..03565415 100644
--- a/tests/Behat/features/non-inline-block-validation.feature
+++ b/tests/Behat/features/non-inline-block-validation.feature
@@ -8,6 +8,7 @@ Feature: Blocks are validated when non-inline saving blocks
     Given I add an extension "DNADesign\Elemental\Extensions\ElementalPageExtension" to the "Page" class
     And I add an extension "SilverStripe\FrameworkTest\Elemental\Extension\ElementContentExtension" to the "DNADesign\Elemental\Models\ElementContent" class
     And I add an extension "SilverStripe\FrameworkTest\Elemental\Extension\NumericFieldExtension" to the "SilverStripe\Forms\NumericField" class
+    And a "image" "file1.jpg"
     And content blocks are not in-line editable
     And I go to "/dev/build?flush"
     And a "page" "Blocks Page" with a "My title" content element with "My content" content
@@ -19,12 +20,19 @@ Feature: Blocks are validated when non-inline saving blocks
 
   Scenario: Non-inline block validation
     
-    # Related has_one RequiredFields
+    # Related has_one RequiredFields with ID suffix (MyPageID)
     When I press the "Save" button
     Then I should see "\"My page\" is required" in the "#message-Form_ItemEditForm_MyPageID" element
     And I click on the "#Form_ItemEditForm_MyPageID" element
     And I click on the ".ss-searchable-dropdown-field__option:nth-of-type(2)" element
 
+    # Related has_one RequiredFields without ID suffix (MyFile)
+    Then I should see "\"My file\" is required" in the "#message-Form_ItemEditForm_MyFile" element
+    When I click "Choose existing" in the ".uploadfield" element
+    And I press the "Back" HTML field button
+    And I click on the file named "file1" in the gallery
+    And I press the "Insert" button
+
     # RequiredFields on TextCheckboxGroupField (composite) field
     When I fill in "Title" with ""
     And I press the "Save" button
@@ -54,3 +62,5 @@ Feature: Blocks are validated when non-inline saving blocks
     # Success message
     When I press the "Save" button
     Then I should see "Saved content block \"My title\"" in the "#Form_ItemEditForm_error" element
+    Then I should see "Home" in the "#Form_ItemEditForm_MyPageID" element
+    And I should see "file1" in the ".uploadfield-item__title" element
diff --git a/tests/Behat/features/page-save-validation.feature b/tests/Behat/features/page-save-validation.feature
index 3bfdd723..e1d2718a 100644
--- a/tests/Behat/features/page-save-validation.feature
+++ b/tests/Behat/features/page-save-validation.feature
@@ -8,6 +8,7 @@ Feature: Blocks are validated when page saving blocks
     Given I add an extension "DNADesign\Elemental\Extensions\ElementalPageExtension" to the "Page" class
     And I add an extension "SilverStripe\FrameworkTest\Elemental\Extension\ElementContentExtension" to the "DNADesign\Elemental\Models\ElementContent" class
     And I add an extension "SilverStripe\FrameworkTest\Elemental\Extension\NumericFieldExtension" to the "SilverStripe\Forms\NumericField" class
+    And a "image" "file1.jpg"
     And I go to "/dev/build?flush"
     And a "page" "Blocks Page" with a "My title" content element with "My content" content
     And the "group" "EDITOR" has permissions "Access to 'Pages' section"
@@ -17,10 +18,16 @@ Feature: Blocks are validated when page saving blocks
     And I click on the caret button for block 1
     And I click on the "#Form_ElementForm_1_PageElements_1_MyPageID" element
     And I click on the ".ss-searchable-dropdown-field__option:nth-of-type(2)" element
+    And I click "Choose existing" in the ".uploadfield" element
+    And I press the "Back" HTML field button
+    And I click on the file named "file1" in the gallery
+    And I press the "Insert" button
+    And I press the "Save" button
+    And I click on the caret button for block 1
 
   Scenario: Validation when page saving inline blocks
 
-    # Related has_one RequiredFields
+    # Related has_one RequiredFields with ID suffix (MyPageID)
     When I click on the "#Form_ElementForm_1_PageElements_1_MyPageID" element
     And I click on the ".ss-searchable-dropdown-field__option:nth-of-type(1)" element
     And I press the "Save" button
@@ -29,6 +36,13 @@ Feature: Blocks are validated when page saving blocks
     And I click on the "#Form_ElementForm_1_PageElements_1_MyPageID" element
     And I click on the ".ss-searchable-dropdown-field__option:nth-of-type(2)" element
 
+    # Related has_one RequiredFields without ID suffix (MyFile)
+    When I click on the ".uploadfield-item__remove-btn" element
+    And I press the "Save" button
+    Then I should see "\"My file\" is required" in the "#Form_EditForm_error" element
+    # Old file will be selected at this point, so don't need to reselect
+    And I click on the caret button for block 1
+
     # FormField::validate()
     And I fill in "1" for "My Int" for block 1
     And I press the "Save" button
@@ -58,3 +72,8 @@ Feature: Blocks are validated when page saving blocks
     # Success message
     When I press the "Save" button
     Then I should see a "Saved 'Blocks Page' successfully." success toast
+
+    # Validate that related data saved correctly
+    When I click on the caret button for block 1
+    Then I should see "Home" in the "#Form_ElementForm_1_PageElements_1_MyPageID" element
+    And I should see "file1" in the ".uploadfield-item__title" element
diff --git a/tests/Behat/files/file1.jpg b/tests/Behat/files/file1.jpg
new file mode 100644
index 00000000..beb5a91b
Binary files /dev/null and b/tests/Behat/files/file1.jpg differ