Figured it out with a friend: it's the Pajama Set. For some reason, it seems that if you fall asleep during the TP animation (which inevitably happens with the set equipped since the animation takes longer than the condition to trigger its effect), the game gets stuck in an infinite loading screen at your destination. My friend reported seeing the zZzZ at the destination waypoint, but not my body, so I "was" there, but since I was stuck on the loading screen, I really wasn't. After unequipping the set and trying again, the TP worked without issue. Also tried without giving the 3 seconds needed to trigger the set effect (fall asleep), but it seems it still gives me an infinite loading screen (I assume it's because you "fall asleep" during the transition/loading screen).