I have some librarians who won't restock their trades. Everything was going well in my world, i had some villagers with 1 emerald trades after they had been zombified and cured many times, but one day the light in my house went off, so minecraft was forced to close. After turning on my pc again, the villagers had the price of their trades changed and after zombifying and curing them twice again, they were not restocking the trades anymore, and still aren't.