I have the same problem. It wanted a government letter or something so I updated my state resale certificate two weeks ago and it was "rejected" yesterday - no email or explanation, just shows "rejected" in the portal. Now the only options it gives me when I retry is ownership documentation of my domain registration. (I don't have a website and that was the other option - website that included my address.)
Weird as I've been a partner and reseller for close to 20 years and all the sudden this nonsense popped up in the portal about a month ago for both my MPN status and CSP.