Checking for effects works with mobs but not with players if effect is only 1t long

So in my datapack I'm checking if a entity has an effect it gets from a tipped arrow, the tipped arrow gives the effect for 1 tick only to prevent a function from running multiple times. With any mobs it works fine but if I do the exact same thing with players it won't work unless I make the arrow give the effect for 2 ticks or more. Is this a bug? I believe it may be caused by the player and the mobs being handled in a different order.