Add on’s don’t work when playing split screen, they go invisible

Me and my friend went onto our old world, which had a few add ons. We’ve had it for a long time now. We use my Xbox one with split screen to play it. After the newest updates the add ons have stopped working. Visual add ons work but if it’s anything to do with blocks or decoration add on’s they go invisible. You can not see them when placed or even in the hot bar.