Unable to respawn or exit game upon death

When I die in any dimension other than the overworld, I get the death screen but the 'respawn' button does nothing. The 'Title Screen' button takes me to the 'Saving World...' screen, but that doesn't change. I waited ten minutes for nothing to happen. It also cannot be closed except when the computer shuts down.

 

If I reboot my computer, it closes the game and I can load it up again.