If you import a mesh with animation enabled with fbx, then the character will not be able to step on this object. There are simply no collisions in this case, it is impossible to configure. Other. I made a cave, a complex mesh, like a curved pipe. There is a natural downward slope and turns. The character can start the game inside the pipe and walk on the floor. But when you deviate to the side, it falls out through the walls … The collision in this case is complex. I think these are bugs.