Interesting. This aligns with my experience. I think it was when I deleted and re-placed the villager's associated workstation. I might have in inadvertently "refreshed" the villager's job_site tag.
LOL, one of my villagers in the Nether did successfully restock and I'm not sure what triggered the restock. Will keep testing. Thank you.
My villagers are located in the nether and each has access to their workstation yet they never restock. Villagers have always performed trades in the nether and the End.
Please tell me that villagers will be allowed to restock in the nether and End even though there is no day/night cycle?! Please!
Found my particular problem.... I had my villagers restrained in minecarts (a classic way to organize a villager trading hall) with their respective workstation next to them. In this configuration, the villagers never restocked. Once I released the villagers and let them wander freely with their workstation close by, restocking worked normally. Even being in the nether, the villagers restock approx every two in-game days.