If you change from Spectator mode to Survival mode, the experience bar and the item you hold is shown but you can't move or interact with anything.

Steps to Repoduce:

For this to happen, you have to be in Spectator mode first. Then click a mob (I chosen a Zombie and Skeleton before), and then change back to Survival mode. Try and start to attack the mob you were by clicking randomly (left-click) and it should happen. The steps to how the glitch happened.