FINALLY FOUND THE ANSWER! Call Apple Support. We can't fix it ourselves. They have to fix it manually over the phone. It took waiting on hold for 3 minutes but it's all sorted now. Use the Apple Developer Contact page to get in touch with them. Visit https://developer.apple.com/contact/topic/select and then select "Membership and Account" then "Program Purchase and Renewal" and then select a call back. I hope this helps!

Hopefully found an answer! I spoke to Developer Tech Support and apparently my App Store Connect account was connected to both my Personal developer account and another Business one from a company I used to be associated. I had to leave that old team's account within App Store Connect and then reload. My association with that account is now severed and hopefully within 24 hours I should be back up and running!

Same issue. Trying to get through to them on phone support.