This is on Combat_TestLive_US3_PvE on PC.
My base on the southern river was attacked by imps in a purge. The first and last wave came along the shore from the east. Instead of attacking my base, they attacked my neighbor’s base, which is adjacent and east of me. Since I was getting the purge notification, I would assume the MOBS would only attack my base. Other waves came from across the river and only attacked my base.