GMEdit creating conflicts with variable definitions set in room editor

[davemakes]

Ok, I've been running into a very specific issue, and I think I've narrowed it down to a weird interaction between the room editor and GMEdit. This is on Windows 10 running GMS LTS IDE v2022.0.1.31 Runtime 2022.0.1.30

I have objects in a room that have a variable definition string. In the room editor, I can edit that string in the inspector, and everything works as expected. If I make a change to that object's code in GMEdit (not the properties, just like the draw event or something), the instances of that object in the room appear to revert back to the default variable definition string. If I run the game, it turns out they haven't lost the definition at all, but it will no longer appear in the room editor.

Here's where things get really weird. If I keep editing the room, and especially if I copy and paste the objects in the room, I sometimes lose the ability to change the variable at all in the room editor. Looking at the room yy file, the instances start collecting multiple "GMOverriddenProperty" lines for the same property with different values. The ones that are changed in the editor aren't always the ones being used when the game runs. The room file is essentially wrecked, and objects have to be deleted and recreated in order to make their variable definitions work again.
room_variable_test.zip

room-variable-test-edit.mp4

[YellowAfterlife]

This is a long-standing GameMaker bug - if the object YY file is changed (try it yourself by adding a space somewhere using Notepad), the room editor loses track of variable definitions until the project is re-opened.