Good news! This appears to be fixed as of Big Sur Beta 7.

Hi @edford, thank you. I ought to have added "I'm going to follow the Restore instructions next", I have those. I posted here hoping there was an easier and less time consuming way to fix the issue. For more follow-up, please use the forums dedicated to the program, which you can access from the menu by clicking on your avatar icon. Did you just add me to that? I did not have access to that before and didn't know about it. Thanks!

Hi Quinn, Thanks for looking into this and responding so quickly. I'm happy to report that I can no longer demonstrate the problem on iOS 15 beta 7. Cheers, Billy

This appears to be fixed as of Beta 6.

Hello, I'm concerned that there has been no action on this bug report in Feedback Assistant. It's pretty bad for our customers when they visit our website and we link them to our app in the Mac App Store using the universal link. I didn't post the URL here before because I don't want to spam things up, but you can see the behavior by opening this URL on macOS 11.6 as well as 12.1 Beta: https://appstore.com/mac/zeteticllc/codebook I tried it again just now and it's still happening. Hopefully it's an easy fix in the Mac App Store? Otherwise we will have to switch back to providing only the link that works for US-store customers, which is not ideal.

Ah ha! Here's what's going on: there's the HTTP status code, and then the responseObject status code, and that's not at all clear in the documentation. The HTTP status code will come back 200, from the production URL when you are supposed to retry with sandbox URL, because that's not the status to check: the 21007 code is the status inside the response object with the status code 200.