When trying to place building materials the blueprint would line up with existing walls/floors etc but as soon as you press action button the installed wall would be of center about a quarter turn, is this a bug ? Any one else ?

I also have this problem. As you described it, that means I want to build a 45 degree piece, the blueprint is okay, then confirm and the blueprint jumps to straight.

Or the blueprint is okay, after confirming it, the Blueprint  jumps 2-3 degrees (floor, walls and stairs).

But this only after a while. I can build 3 - 4 floors normally, then it starts.

 

Please fix this Obsidian.