Cant break blocks

Put the summary of the bug you're having here

What I expected to happen was...:
I was going to be able to break blocks with my enchanted sword.

What actually happened was...:
It didnt destroy the block, it acted as i were in survival, but it never destroyed the block.

Steps to Reproduce:
1. Load a world and enchant a Diamond sword (my enchantment was Knockback 1)
2. Try to break some blocks.
3. Profit