Gamerule mobgriefing false breaks observers ability to observer when a sheep grows its wool back.

On Xbox one in single player mode when have a observer facing a sheep and shear it  and wait when the wool grows back the observer doesn't detect it. On mcpe it detects it and sends a signal to the dispenser to shear it. When I set gamerule mob grieving false neither one will detect it and shear the sheep. When I turn back on mob grieving it works fine on mcpe.