First and foremost, the stacking mechanism is just -chefs kiss-
Amplifies my enjoyment of the game x100.
That said, every once in a while I get a stack of one item when interacting with furnaces, containers, stockpiles, etc and it really throws a wrench into things because the stack of one interacts differently than a single object in some scenarios. Firebrands being the issue that brought me here to the forums in particular, but I've seen it with other things as well.
Something fishy is happening with the stacking when the stack reaches one. Idk. I don't pretend to know.
Just calling it out so maybe somebody might look at it.
Other than that, stacking is 10/10, would stack again.