I have had this problem since I created the realm (about a month ago) but originally I could still upload worlds and packs. Now I can’t change any settings in the “world” menu of realms and I can’t upload any worlds or packs. When I try to add the packs it often says "An error has occured" and when I try to change settings when i try to leave the menu it says "The selected content could not be applied.".

 The world still works, and if I want to change game rules I can use the command. It’s very annoying not being able to upload behaviour packs because we have a few on and we want to add more as the realm progresses.