actually 1.14.2 because in 1.14.4, they don't work in the first place due to world crashing, chunk errors and so on. (maybe 1.15 should fix those bugs, like now.) so either way i have a lot of villagers (fortune, mending, silk touch, and so on.) either way, they restocked just fine, until i put them in a new cell design, which is 1x*2y*1z, making it very cramped, but accessible to a workstation (e.g. lectern). when they were put into this new cell layout, they didn't restock. they stand on top oak slabs and right above their head is a bottom oak slab. the villagers are mostly surrouned by bookshelves like this:

edit: i fought there is a torch where the villagers head is. maybe it involves the torch?