Mac user here.
By now I’ve figured out the pattern of this bug, which has been happening for the last three days.
-Upon a fresh log in, Lion’s Arch loads just fine.
-I leave the region to go do any random thing from dungeons to world bosses.
-Come back to Lion’s Arch, and the loading wheel in the lower right spins indefinitely. I can usually tell because it also does not show the map completion icons on the loading screen, and the loading wheel’s framerate gets choppy instead of the usual smooth spinning. There’s usual a 50/50 chance the game will just out right crash and tell me it failed to load something.
-I quit the game via key command or just using the menu, the wheel halts movement, but I have to force quit the game to actually make it close down.
-Click GW2 to re-open. The Finder word on the top left of the menu is replaced by Guild Wars 2 like normal and my dock shows that GW2 is up, however the window fails to load at all.
-I quit the game via the bar menu, suddenly log in window appears and I can log in again.
-Upon the window coming up, it makes some kind of minor download that takes two seconds, and then I log back in. See step one again.
All other regions act just dandy, and as long as I don’t need to go to Lion’s Arch more than once per log-in, everything is okay.