Dry goods sack minior technicallity

Its a tiny thing, I noticed that if you empty a dry goods bag whilst crafting something, then go and refill it, you have to reselect the item from the menu for the refilled bag to be accepted as a source of flour or whatever. I was making pie dough as it happened, and I manually emptied the last bit of higher purity flour to refill with low purity oat meal, this might be relevant but I doubt it.