West Freeport - Trissa Whistlesong
 

If fighting with a pet and/or hit with an enchanter nuke/stun, she pops up into the 2nd floor. (and can hit from there as well, but eventually runs downstairs)
This was happening pre-patch 39 as well.

Same for me.

Issues aren't limited to that.

I'm engaging currently (9/27/2015) with a monk and after a couple rounds of melee combat, she ghosts up to floor 2. She's still able to engage for a turn or two after that, then paths back to the room.