It dose not let me use a anvil to rename name tags and objects

Sooo.... Pretty much I was going to name my axolotl butter like one would but I couldn't get the name tag to work in the anvil so I started try to rename my sword I also tried enchantments and it wouldn't work so I even restarted Minecraft and also had a friend try and know I can't name butter 🥲. Ps. I think there might be a bug with the anvil and this is also on a realm just so you know 😁.