UPDATE on Teespring (for anyone who cares):
I was able to get to the product pages of some Sapien products by clicking on the Teespring recommendation for a dog tag (which are discontinued and are “Out of Stock,” of course). At the bottom of that product page, there were more Sapien recommendations. When I clicked on the recommendation for an item I knew was in stock (a drink charger), I was able to get to that product page which also had an announcement for the sale and the discount code across the product page.
I was able to use the recommendations along the bottom of that page to navigate to other products, and so on.
A bit clunky, I know, but it’s a work-around we can use now, if we want.