/shop - buying stacks of 16-stackable or less items - stack count is wrong

If you buy/sell multiple stacks of an item that stacks to 16 or less, it lists the correct price, but the incorrect number of items (1 stack = 64 instead of 16, 2 stacks = 128 instead of 32, etc) think this is known for RPG, confirming it's an issue for Factions (same shop plugin)