So I believe we have an explanation for the weirdness we're seeing and it is because of the cart.
What seems to be happening is that if a person buys your shirt and a product from another site in the same purchase, the other product is tallying +1 for your ongoing sales, but ONLY on the artist's stat page. This is what was causing the first day "ongoing sales" on the artist's stat page, as well as ongoing sale weirdness. Our Dev guys have confirmed that it is NOT affecting actual accounting or reckoning numbers, as those aren't registering those additional items as ongoing sales. Those should all be accurate.
They've set up a fix that should go out with the next deployment. I should be getting updates, so if anything else comes up or goes awry, I'll relay it your way. Thanks for catching this one guys, and for the patience.