when you go to the nether your armor points don't show

It's simple and doesn't affect gameplay (I don't think) When you go to the nether and you have armor on, the armor points above the hearts don't show and you have to take a piece of armor off and put it back on to show the bar. This happens sometimes when coming back to the overworld. In the image you can see how I don't have armor showing at the bottom bar but i'm wearing an iron set.