Was Ulfheim dragon change on purpose or a bug?

Previously when fighting the final wave battle in Ulfheim the dragon would stay in the outside area and maybe breathe fire in sometimes. You'd generally clear out the barbarians then head outside to the dragon. This week the dragon started coming inside the building. I can't tell if this was a desired change or if this is a bug caused by some other change.

pros:
-makes the fight a bit trickier

cons:
-looks bad to have him sticking his head through the roof and body through the pillars
-sometimes he seems to get stuck inside when you want to fight him outside

 

@Sannio, think this is your scene? does he have a leash?

 

Yeah, he pretty much flies right in. Except he's a bit too big, and is clipping through the building. And firebombing you through the ceiling.

 

@Sannio, I've also seen this happening in Mysterious Swamp since a patch or two ago, in the kobold house. The giant mechanical monkies are now able to go through walls to enter rooms they'd always been to large to enter before. Seems likely to be related?