The stackable items not stacking issue has been in the game for a long time - i.e. items with the same name not stacking for no obvious (to player) reason. Usually this doesn't cause any issues, but now with textilecraft, it looks like there is a potentially troublesome issue: when extracting fibers from plants, you need at least 15 sets of dried retted plant, but because of the stacking issue, you can end up with something like my current character has with her stacks of 2 and 10 bunches of nettles - she cannot use them to extract fibers, because they don't stack with any other nettle bunches, and you cannot use different sets for extracting (they have to be in the same set), so those bunches of less than the required 15 go to waste. The quickest fix would probably be to allow combining different sets of plants during the extraction phase, until they make up at least 15.