So I’ve been experimenting with unity 6. (Unsure if this happens in other version of unity)
It appears that it’s pretty easy to completely break the functionality of terrain. Essentially every terrain is no longer paintable at all. Resetting layouts, terrain components, adjusting terrain settings, creating new terrains, in different scenes, reloading unity, none of these fixes the issue. The only time it is not broken is in a completely new project.
I tried to reproduce it in another project, and it did eventually completely break again. I still haven’t been able to consistently reproduce it with specific steps. Primarily it involved having two inspector windows open, then closing the project, opening the project, closing/opening multiple inspectors, using the “make this inspector active” that pops up when painting and changing inspector windows, and repeating that until it just decides to permanently no longer function. Trying to paint anything will just deselect / reselect the terrain. The usual painting brush is not visible when hovering over the terrain and no errors or warnings are shown.
Originally the issue happened in a project where I was testing out Entities, and then I reproduced it in a normal non-entities project. I was able to recover to an editable terrain in the non-entities project, but the entities project the terrain is still completely broken.
As a work around since I’m just experimenting anyway, I just imported everything into a completely new project and that seemed to work, but obviously that isn’t a fix. I guess I’ll just hope it doesn’t happen again.