Good afternoon. Help out a newbie. I made a plan for a friend of his apartment of a strange shape. Very few flat walls. What I noticed - I can’t smoothly change the angle of the wall, it changes in jumps, maybe I’m doing something wrong? I also have an incomprehensible artifact in the form of 3D on the ceiling. And with the levels, I set the problem to “Make all levels visible”, but the floor texture at level “0” is not visible. Tell me what am I doing wrong?

Link to file

https://ibb.co/6YLWFzn

https://ibb.co/wpZfgBc

https://ibb.co/HHwVJ6C