Add-On Bug

When I pick up any items which are part of an addon, all buttons disappear and I can't see any dropped items, my player's hand, my paper doll, etc. I can still move around but I can't get the add-on block to work. If I put it into my hotbar, as soon as I exit the inventory, it happens. Movs also disappear, I can only see their shadows. I haven't seen any fixes on the internet for this but I know it still happens as I've seen on the comments of the behavior packs. Thank you!