Every so often my deluxe coop and barn is failing to auto-restock the hay piles, during fall season, seems like maybe once a week, still trying to figure out if it is related to any in-game events. I think my animals can't eat the grass on the standard farm map because it is too far away, so they are eating hay instead, but every so often it's not getting replaced by the auto-stocker, and I have to do it by hand.
I can reproduce this issue during the fall when some animals are allowed to eat fresh grass, but others are not; the auto-feed system will not refill the eaten hay overnight.