Export var Arrays of Arrays will not allow elements to be added to sub arrays in tool scripts

[A-Hugh-Mann]

Godot version

4.0.dev.b4ac381f3

System information

• OS: Arch Linux
• Godot Version: 4.0.dev (b4ac381)
• Rendering Driver: OpenGL API 4.6 (Core Profile) Mesa 23.0.3 - Compatibility
• Rendering Method: Compatibility
• Graphics Card: AMD Radeom RX 6600
• Graphics Card Driver: navi23 (amdgpu)
• CPU: AMD Ryzen 8 5900X

Issue description

If you create a @tool script and export a var that is an array of arrays, upon clicking add element, the element that was added will disappear almost immediately, preventing you from adding anything to an array from inside of the editor.

Steps to reproduce

Create a new scene with a node of any type.

Attach a script that is a tool script with an exported var of type Array[Array], example:
@tool
extends Node
@export var test_array: Array[Array] = []

Click on that node and attempt to edit that test_array property in the inspector.

Click + Add Element to add an Array to that Array.

Click on the upper + Add Element or, click up arrow next to size, to attempt to add an element to that inner Array.

Minimal reproduction project

N/A

[A-Hugh-Mann]

Duplicate of #76642