Do you have a meta.lsx at this path? \Steam\steamapps\common\Divinity Original Sin 2\Data\Mods\YourMod
Does it have any content if you open it in notepad(If its there?)
Yes, the meta.lsx files are present, their contents look as expected with correct names and such.
Yes, I have tried creating a new project (I mentioned this in the first post) and it did not change anything, the button still doesn't work even in the new project.
Pretty unfortunate circumstances.. any mods I have been making are on hold until I can figure this out. I can't access the project settings window to change things or add a thumbnail or any of that.