Steps to Reproduce:
Grab any item, such as a glass block or anything.
Grab an anvil and place it down
Grab sharpness, smite, and bane of arthropods books
Attempt to combine all of the books on the chosen item
Expected Result:
The item can receive conflicting enchantments only in creative
Observed Result:
The item cannot receive conflicting enchantments, regardless of the gamemode.