Thanks for the reply.
It is not just an NA issue, don't worry.
The easiest to notice these wall breaking behavior is in the 4th Maelstrom stage where there is an obstacle right in the middle of the map, and mobs just pass right through it.
I had serious trouble stacking mobs in vHoF HM because of this issue; they would simply walk down the platform instead of going all the way around like they should.