...if you only need one star to reach the next level of mastery.
I've seen a number of folks complain that mastery spice hasn't worked for them with the current Game of Scones event. It's worked fine for me, but I wanted to remind folks a common reason why you won't get 2 yellow stars out of a mastery spice.
So, y'all, remember! If you only need one star to reach the next mastery level (like in the attached picture, as an example), do not use mastery spice. It will be wasted, you will only get one yellow star, you will be sad, and you will be forced to complain on the forums to no avail. Don't let it happen to you!!