Get error "stack is empty" on v15-preview

[NotAwar]

running version 15 preview:

configuration (omitted some info):

  "ChangeSetMappingFile": null,
  "Source": {
    "$type": "TfsTeamProjectConfig",
    "Collection": "https://dev.azure.com/*/",
    "Project": "Portaler",
    "ReflectedWorkItemIDFieldName": "Custom.ReflectedWorkItemId",
    "AllowCrossProjectLinking": true,
    "AuthenticationMode": "Prompt",
    "PersonalAccessToken": "",
    "PersonalAccessTokenVariableName": "",
    "LanguageMaps": {
      "AreaPath": "Area",
      "IterationPath": "Iteration"
    } 
  },
  "Target": {
    "$type": "TfsTeamProjectConfig",
    "Collection": "https://dev.azure.com/*/",
    "Project": " test pos",
    "ReflectedWorkItemIDFieldName": "Custom.ReflectedWorkItemId",
    "AllowCrossProjectLinking": true,
    "AuthenticationMode": "Prompt",
    "PersonalAccessToken": "*",
    "PersonalAccessTokenVariableName": "*",
    "LanguageMaps": {
      "AreaPath": "Area",
      "IterationPath": "Iteration"
    }
  },
  "FieldMaps": [],
  "GitRepoMapping": null,
  "LogLevel": "Debug",
  "CommonEnrichersConfig": [
    {
      "$type": "TfsNodeStructureOptions",
      "PrefixProjectToNodes": false,
      "NodeBasePaths": [],
      "AreaMaps": {
        "^Portaler\\\\(.*)": "test pos\\\\$1"
      },
      "IterationMaps": {
        "^Portaler\\\\(.*)": "test pos\\\\$1"
      },
      "ShouldCreateMissingRevisionPaths": true,
      "ReplicateAllExistingNodes": true
    }
  ],
  "Processors": [
    {
      "$type": "WorkItemMigrationConfig",
      "Enabled": true,
      "UpdateCreatedDate": true,
      "UpdateCreatedBy": true,
      "WIQLQuery": "SELECT [System.Id], [System.WorkItemType], [System.Title], [System.AssignedTo], [System.State] FROM WorkItems ORDER BY [System.ChangedDate] asc",
      "AttachmentMigration": true,
      "AttachmentWorkingPath": "c:\\temp\\WorkItemAttachmentWorkingFolder\\",
      "FixHtmlAttachmentLinks": false,
      "SkipToFinalRevisedWorkItemType": false,
      "WorkItemCreateRetryLimit": 5,
      "FilterWorkItemsThatAlreadyExistInTarget": true,
      "PauseAfterEachWorkItem": false,
      "AttachmentMaxSize": 480000000,
      "AttachRevisionHistory": false,
      "LinkMigrationSaveEachAsAdded": false,
      "GenerateMigrationComment": true,
      "WorkItemIDs": null,
      "MaxGracefulFailures": 3,
      "SkipRevisionWithInvalidIterationPath": true,
      "SkipRevisionWithInvalidAreaPath": true
    }
  ],
  "Version": "15.0",
  "workaroundForQuerySOAPBugEnabled": false,
  "WorkItemTypeDefinition": {
    "sourceWorkItemTypeName": "targetWorkItemTypeName"
  },
  "Endpoints": {
    "InMemoryWorkItemEndpoints": [
      {
        "Name": "Source",
        "EndpointEnrichers": null
      },
      {
        "Name": "Target",
        "EndpointEnrichers": null
      }
    ]
  }
}```

This has worked previously, i don't understand exactly why it's not working, but when i run it i get:

[13:41:02 DBG] [v15.0.0] Node \test pos\Area* already exists
[13:41:02 INF] [v15.0.0] DONE in 00:07:13.1953595
[13:41:03 FTL] [v15.0.0] Error while running WorkItemMigration
System.InvalidOperationException: Stack is empty.
ved System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
ved System.Collections.Generic.Stack1.Pop() ved MigrationTools.Enrichers.TfsNodeStructure.GetOrCreateNode(String nodePath, Nullable1 startDate, Nullable1 finishDate) i D:\a\1\s\src\MigrationTools.Clients.AzureDevops.ObjectModel\ProcessorEnrichers\TfsNodeStructure.cs:linje 202 ved MigrationTools.Enrichers.TfsNodeStructure.CheckForMissingPaths(List1 workItems, TfsNodeStructureType nodeType) i D:\a\1\s\src\MigrationTools.Clients.AzureDevops.ObjectModel\ProcessorEnrichers\TfsNodeStructure.cs:linje 593
ved MigrationTools.Enrichers.TfsNodeStructure.GetMissingRevisionNodes(List`1 workItems) i D:\a\1\s\src\MigrationTools.Clients.AzureDevops.ObjectModel\ProcessorEnrichers\TfsNodeStructure.cs:linje 634
ved VstsSyncMigrator.Engine.WorkItemMigrationContext.InternalExecute() i D:\a\1\s\src\VstsSyncMigrator.Core\Execution\MigrationContext\WorkItemMigrationContext.cs:linje 190
ved MigrationTools._EngineV1.Processors.MigrationProcessorBase.Execute() i D:\a\1\s\src\MigrationTools_EngineV1\Processors\MigrationProcessorBase.cs:linje 49
[13:41:03 ERR] [v15.0.0] WorkItemMigration The Processor MigrationEngine entered the failed state...stopping run
[13:41:03 INF] [v15.0.0] Application is shutting down...
[13:41:03 DBG] [v15.0.0] Hosting stopping
[13:41:03 DBG] [v15.0.0] Exiting with return code: 0
[13:41:03 INF] [v15.0.0] Application Ending
[13:41:03 INF] [v15.0.0] The application ran in 00:07:49.1416450 and finished at 02/26/2024 13:41:03
[13:41:03 DBG] [v15.0.0] Hosting stopped