Hey
I wanted to let you know that UE-15516 is still an issue within our editor, so if you’ve started using grouped items and you notice pivot is acting strange, it’s because of this bug.
However, I did check BSPs in 4.8.1 and I have yet to be able to replicate issue with pivot moving away from BSP. Have you tried upgrading to 4.8.1?
Looking forward to hearing back from you, thanks! 