Mesh collider forgets the mesh

I have kind of a strange problem here:
In my scene I have an object (the ground, on which a robot is driving), that has a mesh collider attached.
It works fine so far, but when I reload the level, the meshcollider has forgotten, which mesh it has to use in the setting “Mesh”.
I tried to add the mesh a second time, and that seemed to work, but it is still confusing. And i am not sure, if it may happen later again.

Does anyone have an idea, why the collider may forget the mesh?


is the floor a prefab of some kind at all? if so try adding the mesh to the mesh collider again and press the “Apply” button near the top of the inspector.

my guess is that problem might be caused by unity loading a prefab where the mesh for the collider was not assigned thus it makes it “forget” it. by applying the mesh to the prefab… it assigns it to the prefab so it will hopefully rectify your problem.