I have been having the same exact issue! I have noticed that sometimes rebuilding the lighting will work to solve it but then it reverts back to that state later. Also when it comes to those green squares in the third picture. I noticed it happens when i have the Guardian Space enabled. I hope someone can shed some light on a fix soon!
I have same issues. I sometimes get the green squares on the walls, black textures instead of proper textures for meshes, weird red triangles combined with black for some textures.
got the same issue, it keeps happening whenever i put a material on any objects, or if the nav volume is moved. Would be amaizing if anyone could help 🙂