I brought up the same to Nico on Discord and he replied that they are aware of it and have a ticket open. This was on the "Daily Deal" or whatever you call it on the main landing page. I tried it 3 times just to verify that I got the award for the Daily Goal for "Make a Purchase in the Pro Shop" and that I did get the apparel points I was owed each time, and I indeed did.
So it's just an annoyance at this point, but I'd never be buying Apparel from here again anyway. I just needed to make a purchase and noticed they had the SE Hat available so took a shot in the dark.
For normal apparel purchases through the Sponsor's tabs it still works as it should and you can use the back button without having to completely close down the app.