They told me that equipment doesn't stack and items from different sources won't stack such as items from the crown store won't stack on the same item from crown crates. I made several bows of the same kind trying to increase my crafting and none of them would stack. I showed him that and he tried it himself and his wouldn't stack either. He then said that they were equipment so that's why they won't stack. If this is the way it's meant to be they should change it. I have to put most of my stuff in the bank so it doesn't take up all my space in my bag. Strangely I have a stack of buff food in the bank from the crown store that won't stack with the same in my bag. I don't think they want to hear it.
If the food items are identical, I'm a little surprised they don't stack. That might indeed be a bug. Or maybe it's because the Crown Crate items aren't identical as they can be turned into gems and Crown Store items cannot.
Weapons, armor, and jewelry have never stacked and it is irrelevant if they are bound or not. Weapons most often have glyphs that wear down and need to be recharged. Armor wears out and needs to be repaired. Since both of these functions require a unique identifier so their wear can be tracked they are not able to be stacked.