IndexOutOfRangeException when creating a new Terrain Layer

Hello,

iam not sure if this is the right area for my problem.
But when iam creating a new Layer for my Terrain i cant select it to paint textures. Its throws an
IndexOutOfRangeException.

I dont know if i do something wrong, but there were no problems with the other 3 layers i created.

I made a Video:

iam using the newest LTS version (Unity 2021.3.5f1)

Thanks for help

It says it’s a problem with something in UnityEditorInternal, so you should just submit a bug report to Unity.