Since Homestead, crafted food and drink have the creator's name on them. This prevents them from being stacked. It is probably due to the new Provisioning furniture having names, and regular food not being properly re-flagged. Before Homestead you could stack created food regardless of who crafted it. This is causing banking nightmares.
In the image below, the stack on the left was made before Homestead (note no created by name). The one on the right is new. The two cannot be stacked.
@ZOS_GinaBruno