@cashew the action of clicking the potions before hand only works in cases where there is a single mob, because when you kill the mob it clears all items,players, and mobs clicked that would otherwise show above the use button. That is what I think should be fixed from my personal experience.
For example when you are in uw surrounded by mobs and you use a potion because you are so close to death then you are waiting for that moment when you can use another, you kill a mob, and then you don’t have the time to reselect and use before another kills you. That has happened several times to me because it clears your selected item upon killing something. Hate when that happens.