Maybe they have an agreement with certain companies to use them and that changed recently?
The issue doesn't appear to be related to agreements with specific companies. Keep reading to see why.
I just opened a case with Samsung Pay Support to make sure they were aware of it. They initially had me delete the membership card and then clear the cache on the Samsung Pay Framework and on Samsung Pay itself. Once I did that they had me add the card back in and they said this has resolved the issue for other people.
I did that and then went to the same grocery store and I still had the same problem. I'd be interested to hear if this resolves the issue for anyone else but I doubt it.
I also had the Beep'N'Go app on my phone and the same Shoprite card loaded in there. I tried that and it worked immediately. Beep'N'Go uses the same Mobeam technology that Samsung Pay uses (built into Samsung phones) so that means that functionality is still working. The issue is clearly with the Samsung Pay app itself. It must not be formulating the barcode correctly. Beep'N'Go is what I used to use before Samsung Pay supported membership cards so I'll probably go back to that until they fix the problem.
It can't hurt to call and open a case for yourself so they understand the issue is widespread. The number for Samsung Pay Support is 844-726-7297.