Realm 500: Internal Server Error (can't change any settings at all)

Me and my friend are trying to play in Minecraft Realm. My friend purchased a realm. However when he makes one, it's set to "peaceful" so nothing spawns. when we want to edit the settings of this realm through "Configure realm" > "World options" and change the difficulty to "Normal", turn Spawn Monsters "on" etc and hit the "Done" button, we're getting an error. it says "Realms (500) Internal server error"

I attached a GIF of the process and error itself.