Enchanting a book can give you Piercing and Protection in one book, which you can not use then.
Step 1: Is to get a book and select the highest level in the enchantment table.
Step 2: Is to wait, if you see Protection 3, that was on my case see if you get Piercing 4 on the same book aswell.
Thank you for your report!
We're tracking this issue as MC-30767, so this ticket is being resolved and linked as a duplicate.
That ticket has already been resolved as working as intended, which means this is not considered a bug and won't be fixed. Please do not leave a comment on the linked ticket.
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