Yes, this is my fault. I set the coordinates from the wall properties edit menu. Zooming in, I saw a gap. By removing it with the mouse, I was able to create a circular room. True, in the figure it is displayed multifaceted, but in the general view it is round.

Sent a file with a small example by mail.

I created a round wall and I just can't make a room
Double click doesn't work!
The multifaceted room does not suit.