What's going on with Bsp brushes?

since 4.7.3 I have a strange bsp behaviour when I create new bsp it has some “additional” empty faces…which completely ruin all bsp brashes on level.

BTW yesterday saw a video on some guy has the same problem with bsp…
https://www…com/watch?v=1Fg_jlcuDAs

Hi ,

I was able to reproduce this and have entered a bug report, UE-13571 to be assessed by the development staff.