Villagers are not refreshing their trades correctly. The sound will play to indicate that they have successfully refreshed their trades, but then they do not. They will eventually succeed in resetting their trades after several failed refreshes. This affects both pre 1.15 and post 1.15 villagers.
Linked issues
duplicates 1
Comments 2
See MC-167002.
"When a villager reaches its own job site block, it commences "work". Two times a day, this action of working resupplies any locked trades."
Are you confusing "working" with resupplying locked trades?