Happened when I tried to teleport from Limsa to Uldah, eventually got an error message, relogged back online only to be UNDER Uldah walking through walls, finally hit the ground outside Uldah and my location finally stuck, lol.
Changing gear while moving on terrain at certain angles will cause you to clip through the ground. The is easy to do on the path from Horizon to Ul'dah on the ramp outside of Horizon.
Happened when I tried to teleport from Limsa to Uldah, eventually got an error message, relogged back online only to be UNDER Uldah walking through walls, finally hit the ground outside Uldah and my location finally stuck, lol.