AR Foundation "Camera Rainbow Disorder" on ARSession.Reset()

Hello there!

I have a problem, when resetting the ARSession. I get a "rainbow disorder" which maybe has something to do with the camera texture, because you cant see it, if there is some GUI above.

Do you guys may know how to avoid this? I attached one image, so you can get a better idea about the problem.

It always appears when calling arSession.Reset(), or sometimes when reopen the Application and you´re in the active Session Screen.

Every suggestion would be Great - Thank you very much!