The villagers won't plant the crops

What I expected to happen was....
Villagers find that there's a matured crops they will harvest crops and pick crops up into their inventory
What actually happened was...:
Villagers find there's a matured crops they want to harvest them, but the bug makes him cannot harvest them , villagers just look at the crop-block won't move
Steps to Reproduce:
1. create lots of matured crop-block
2. put a farmer near that block
3. wait for a minute you will see farmer won't harvest crops

uh it's my first time to reporting bugs to mojang hope you will understand
ps : I am a chinese..