Tradesman Lyna and Sir William walk through/ignore walls

[Thulghor]

Was hanging out in North Freeport around the bank area, and I noticed that Sir William (a North Freeport guard) and Trader Lyna were loitering around the bank. I figured someone might have aggroed them. However, as they returned to their normal places, instead of like, walking around obstacles (like buildings, barrels, walls), they just ghosted through them as though they didn't exist. It was weird looking. Not the usual "run at wall like a blind person until phase through" thing that some mobs do either.

[Thulghor]

After watching some mobs chase an Iksar around North Freeport, quite a number of NPCs (Jade, the "Sir" guards, etc.) just ghost through walls. Not the "run at walls until you pass through" thing either. It's like the walls don't exist for them. Only time I see a guard even open a door to go through anywhere is the bank. Rest just ghost through.

This doesn't seem to be the case in West Freeport, as I see people constantly trying to kill militia guards or Lucan, and those guards seem to react as expected.