I was doing a wool farm when I ran into this problem.

1.Put the sheep with everyone else on top of 5 blocks of earth, surrounded on 4 sides with glass.
2. Then I removed 1 from the sides of the crus and put an observer to observe the grass block and on top of that observer he put a dispenser.
3.Behind the observer put a random block that can transmit the redstone signal to the dispenser with a redstone on top.
4.Finally I placed the sheep in the middle on top of the grass block and this bug occurred when eating the grass the sheep did not turn the grass block into a dirt block it continued the same as it was.
5. I tried to recreate this same mute with the same version and after changing the export my builds to this same world the bug continued.