Bug? Scene view control bar buttons disappear, Version 2021.2.5

During play, at certain times, the buttons on the control bar for the Scene View disappear! (See below). They then come on back on some time later. This seems to involve certain camera positions, but not sure.

Normal:


Bug when rendering certain items during play:




This would not be an issue (and I probably would never have noticed), but for the fact when this happens, my UI Toolkit document object also disappears from the Play window! Everything else seems to work as designed, and the game continues to run, other than this.

Other than using the UI Toolkit, most everything else is the same, which works fine under 2021.1. I really want to use the UI Toolkit, so don't want to go back to 2021.1, if possible.

Don't think this has to do with the UI Toolkit necessarily, since when I delete that object, the buttons still disappear a noted. However, it seems like the UI Toolkit object in the Play view is the only thing which follows the issue with the control bar buttons.

Machine: MacBookPro (2015)
ALSO: MacBookPro 2021 - M1 Max
OS: Catalina, Monterey
Rendering: URP
Unity Versions: 2021.2.5, 2021.2.6

 

OK, I found a way to fix this, but I think this is the result of a Unity bug. Many of the objects in my scene have materials which are TRANSPARENT, so I can fade them in and out. When this is true, the bug manifests itself. If I change the material settings to Opaque, the bug disappears (although my objects don't, since they no longer fade!).

So the bug has to do with: Transparent materials, in URP.

 

Not sure what to do at this point - I have narrowed the problem to one particular object! It seems fine - really a simple object (a rocket engine part from "Ultimate Spaceships Creator")! In Blender, it says it is a manifold, etc etc. Other objects work perfectly. But this particular thing will cause this weird bug in URP rendering on occasion. If it transparent, it manifests a lot more, but still, even opaque, this condition will happen.

 

Found the problem! One of the scale values (X, in this case) was negative. Making it positive (in the Inspector) seemed to fix everything. Soooo, dear neighbors, this seems like a Unity Bug - if it doesn't like negative scales, it shouldn't let me use them, or give an error message or some sort. And it certainly shouldn't cause all this weird, hard-to-track-down behavior.

 

Filed bug with Unity. They created an issue: https://issuetracker.unity3d.com/product/unity/issues/guid/1389888/

 

Note from Unity:

It's now fixed in 2022.2.0a1 and above.

 

Closing the scene view and adding it back solved the problem for me