As the title says!, I have been hearing players say it, and now experienced it myself:
Sometimes there’s a random invisible wall you cannot walk through at the map Stronghold. Close to the doorbreakers and archers spawn not allowing players to leave that place (or trying to somehow find a gap in the wall). This of course limits play quite a lot.:P
I heard stories of other peoples where the wall appeared at other places closer to the lord.
Hope you can fix this Anet!,
I really enjoy HoT so far:P
Strategist