Using anvil to combine enchanted items results in missing enchants

I have a power v/unbreaking III bow, and a mending bow. Attempts to combine these in the anvil does not add mending like previous versions of minecraft.

I also have a simular issue with a fishing rod where I have lure II and unbreaking III, when I combined with a mending rod the lure II vanished. Also attempts to combine with a luck rod shows the result would only be mending+unbreaking III.