Reported by players on my server, but I'm having trouble isolating and duplicating it. The reported issue, if you enter a sending pad that has 3 blocks vertical airspace and a solid ceiling above while on horseback, the pad will spam the message "left the teleport area". Testing myself, I can't get it to spam the message, but it does do it once or twice before the teleport finally activates.

I did find another issue during my testing though. Teleporting on horseback to one of my distant pads results in me arriving without my horse and me floating in air unable to move. Other players see me on horseback as expected, but I'm unable to move and don't see my horse. Relogging fixes the issue and the horse is present. However, when trying to do this from a local sender (short distance) to that same receiver, it behaves as expected. Sending and receiving pads are buried one block down, though I've tried removing that cover on the sender and it doesn't make a difference.