Villager can't regenerated item back

My phone is Samsung Galaxy J3 Pro

Ok I meant villaget can't regen item back are when you trade to villager it will make particle effect.And It will open his trade.Like if I buy emerald it will close when I buy soo many and I trade other trade it will open back.I found this bug when I play map"Island in the sky".I have check villager entity data in blocktograph and it say this villager can regen item back but when I trade it not play particle and it not regen item back

P/s sorry my grammar bad