True! Used to have an A/C unit with this problem. Covering the IR emitter with a finger would desync the remote's state and that of the actual unit. Temperature was the easiest to sync back: just keep lowering it until both systems reach the temperature floor.

This problem still shows up today in limited forms. I have several A/C units of the same model and the same remote. Sometimes the remotes get mixed up and I end up trying to use a remote in the A/C off state to control an A/C that's on, and it does nothing because the remote ignores most button inputs if it thinks the A/C is off. I have cover the IR emitter and "turn it on" first.

On the last sentence, I don't know if you have to cover the emitter