Bug Error loading window layout leads to weird editor UI issues on Unity 2020.2.0b5.3233

I'm working on a new 2D game using 2020.2.0b5 and I've been having this issue where every time I open the project I get this error:


I have to revert factory settings and then close and reopen the project which gets passed that error (but all my layout changes are lost) and then I have these really weird UI issues:

There are two Unity editor "windows" open and one is a blank white screen:

You can see both on the task bar:


Then periodically both screens just go black and I can't see anything:



Sometimes selecting something from one of the menus on the menubar will "fix" the display but other times I have to exit the editor.

I started noticing this after I added Timeline to my project. I'm not sure if that's related or not.

 

Same here, in Unity 2020.2.0b11 and Unity 2020.2.0b12

 

I have not had this issue since I upgraded to the new alpha. It also fixed and issue where the WebGL game wouldn't load on itch.io.

 

Whenever I open a Unity project now, now matter what version of Unity it is, when I hit play it all goes black except for the Play Window & I can't see any of the Play control buttons to stop it playing so have to exit the project to stop it. I tried loading the default layout instead of my custom one & deleting layout files in both project & appData/Roaming/Unity/..../Layouts/ but that hasn't helped either.