Chest bug in nether?

I’m not really sure what the problem here even is. Basically, I entered the nether, grabbed a red mushroom next to the one in the video, opened a chest, and whatever that loading bar thing is appeared. I could move but couldn’t open any menus or scroll through my hot bar. Eventually I had to close the game and relaunched it. Also note I was having internet issues and it’s a visible world (as in my friends could join, but none of them had).