Villagers do not restock.

A likely explanation, given that it appears you’re in a trading hall, is that the villager in front of you switched its workstation with another nearby villager of the same profession MCPE-131043. Since the villager can’t actually pathfind to its workstation, so it has no means of refreshing its trades.

I think it’s not the reason…

In that case, are you able to provide a copy of the affected world? Someone else reported similar behavior a while back MCPE-188052.

I’d try breaking (and placing back down) one of the villager’s workstations to see whether it re-links to it or not, and wait to see whether it starts restocking its trades again.

Sure! https://drive.google.com/file/d/1kR_LnS7gnvgA3liPuojxb1KKQur-uM23/view?usp=sharing

In fact, when I opened a new world, the villagers had no goods at the beginning, even though I never traded with them. That’s why I think it’s a bug.