Non-enchanted tools and armor cannot be combined for repair in the crafting area. Can be combined on an anvil still, but with the added cost of experience levels.
Linked issues
duplicates 1
Comments 2
Duplicate of MC-46447
MC-46482
No longer able to combine non-enchanted items in crafting area
Resolved
Duplicate
0
Confirmed.
Also tested combining two enchanted items and one enchanted and one not on a crafting area (commonly used to remove all enchantments if desired), neither work. I'm wondering if intentional though...