In another thread on this topic, a user mentioned that they had success by submitting a new version and appealing it. I'm trying that right now and will report back. https://developer.apple.com/forums/thread/678920?page=2

Yes, I was able to overcome this by appealing the rejection with the App Review Board. They approved my binary, which broke the cycle of denial and allowed me to set the App Privacy settings appropriately prior to my next binary submission. I’ve filed a feedback documenting the issue and uploaded the details of that feedback here http://openradar.appspot.com/radar?id=5009431033020416

Just wanted to share my experience: Tried generating a promo code, didn't work. Tried generating again immediately after, still didn't work. Tried a third time—worked. So I guess the moral of the story is... just keep trying. App Store Connect surprises me in new ways every day.

The following Terminal command worked for me: rm /var/folders/*/*/*/com.apple.dock.iconcache rm -r /var/folders/*/*/*/com.apple.iconservices* killall Dock