Villagers are refusing to trade when putting the exact number of required items in a trading slot. They however accept the trade if 64 items are put but take more than what the villager advertises. For example, if a Cleric is selling 1 emerald for 3 gold ingots, putting 3 gold ingots will not work while putting a stack will but the villager will take 10 gold ingots for 1 trade instead of taking 3. See this video by Bite The Apple who discovered this as well one month ago : https://www.youtube.com/watch?v=VGvFBqfVjBo
Environment
Under a village (dug an area) where I transported all the villagers of the village by minecart. The villagers (clerics) are confined in a an area where they can walk and access their stations (brewing stands) to reset their trade. They are also each assigned to beds that are placed nearby.
Duplicate of MC-151282