I've been doing lots of caravans when leveling my alts. Thing is not about exact squares. I've noticed it's a bugged spawn places on some of city maps. Usually I'm able to rejoin caravan after some walking around on WM and when I spawn in I notice also guards missing (no bodies), and caravan master is standing next to obstacle like car (no place for some players to spawn in, and some of the guards). It can happen also in desert mountains, when big rock tile happens to be in spawn point.