Shield does not appear enchanted after combining with banner

In my world I had a shield which i enchanted with mending and unbreaking 3 and I decided to put a banner on it. However after combining the 2 the shield no longer had the animated shining purple affect. This is just a small bug that is not game breaking, but i think it is worth mentioning in hopes that it will get patched eventually because it would look really cool to have a shield with both a banner and the shiny animated effect from enchanting.