An issue has occurred where when the player was supposed to wake up, the player instead got stuck sleeping. From the original reporter, this had only been encountered when sleeping in the medium.
I managed to reproduce it once on a locally hosted server with one wake player in the overworld and one in the medium sleeping. It would get stuck with the sleeping gui and nothing would happen when clicking the leave bed button. Waiting out sunrise or breaking the bed did not give any results in waking the "sleeping" player, who appeared to have turned invisible. After leaving and rejoining the server, the situation was back to normal. I did not manage to repeat the issue after trying to repeat the same procedure.

It is not certain that this issue still exists on the current version. If it does, a new issue should be opened.