Just happened to me. Teleported to a player and was stuck and dead immediately after.
When respawning I was under the map and couldn't move.
Turned off vanis and respawned again, respawned on the map then but couldn't move still.
Same after another respawn.
Btw. the player I tried to teleport to was on a motorboat as far as I know.

How did you teleport to the player? Did you use a teleport command or a plugin ?

I used Player Administration.
You think I should mention it there?