1. drag 2 BSP brushes into the map
2. rotate one of the brushes 90 degrees
3. switch to geometry mode
4. select verts from both brushes and move them
5. the verts on the brush that has been rotated will translate locally
instead of in world space
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-7507 in the post.