when a potion which is not a final stage(for example awkward potions) is almost finished brewing. if you spam shift click your next brewing ingredient so that it will go into the brewing stand as the first one disappears the item will go in as expected but the potions below will look like they have not been effected by the first ingredient. this corrects only when you take the brewed potion out of the brewing stand and it will turn into the potion that is the combination of the ingredients that were put in.