What I was doing: Attempting to combine enchantment books at an anvil, of any kind.
What I expected: The two books would combine into a higher level enchantment book.

What happened: The books would combine and then suddenly lag back into their place in the anvil, the same level. I would lose three enchantment levels that I would gain back when logging in. The anvil said I could combine the books, but it wouldn't let me.

How to reproduce: On multiplayer (haven't tested out on single) attempt to combine two enchantment books of any kind that can go up another level on an anvil. Click on it or shift click or do anything to get it into your inventory. It simply won't do it.