Ok so I'm confused. What exactly is "Sync All Quantities" supposed to do?

When i first clicked it, it set all my products to 0... which i figured was because there werent specific attributes defined. So I added one and clicked it again, nothing. The added attribute stayed the same(20), but the other shirts stayed at 0 with no Variants showing.

I tried clicking the products specific "Sync Quantites" as well. Still nothing.

I just installed version 4.9 although I did notice that the instructions were for 4.7ajax. Am I missing something?