villager can only get 4 packs of 64 items, instead of 8

villager can only get 4 packs of 64 items, instead of 8.

I was trying to make a farm of wheat with villagers, I tried to put all the seeds in villager's inventory, but he only gets 3 packs of 64, before he could get 8 packs.
and when they harvest the plantation they get the wheat even with the full inventory.

I can only get the farmers to take 4 piles of seeds and end up getting the wheat and stop working. My 1.14.2 farmers who had 8 piles of seeds in their inventories also stopped working.