Similar experience.

Had an app reviewer when my app first launched, who was complaining that 2FA was failing for them, so they couldn't allow the app to go live.

I was livid. It had worked for EVERY beta tester.

It turns out it was 100% the tester's fault. It "mysteriously" fixed itself. Aka, they realized that the 2FA was via email instead of SMS and finally after 2 weeks of back and forth, passed the app.