Probably a bug in some potions brewing

Hi, today when I was brewing potions for the first time, maybe that was a bug. When I tried to put a potion of damage II on the brewing stand (to make it a splash potion) the potion don't go to the stand (later, I saw that some other potions at the same stage also did the same thing), but the only way to make it a splash potion is to make it towable before it reach the stage II, and I think this is a bug (I opened a new ticket, because the first one was in portuguese). Thank you.