I today saw a big in my anvil.   It shows any object placed inside as invalid by giving the red "X" as soon as the object is placed in the first slot. 

Attempted with:

Diamond boots

Iron Hoe

Netherlands Boots

....etc

ANY object placed in Anvil reads as invalid even before the second object... whether repair or enchantment book.

This is on REALMS OR Standalone.... in Survival mode....Android Bedrock.

Attempted uninstall and re-install without keeping data.   No change. 

1.21.51

Images attached. 

1st two images are from Realms.  2d two are from Standalone.