I can´t hit with my sword on Minecraft.

I went on many different servers, mostly PvP, and I realized that something was wrong- I couldn´t hit!!!
What I expected to happen was...: That I could hit, and hit cows to get food and everything, my sword didn´t move!
I thought that I could hit and everything would be alright.

*What actually happened was...: The sword didn´t move. *

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
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