Test Flight won't let us add testers and submit for review

On 28th October as we were uploading a new build to Test Flight suddenly all of our previous versions and builds expired. We are able to add new builds from Xcode and the build appears as "ready to submit" but when we try to add a tester or a group and submit for review, we get the error "There was an error processing your request. Please try again later." We imminently emailed Apple support and today we got a response saying there has been a brief period causing this error and we should be fine now. However, we're still getting the same error and we haven't been able to add any testers to our Test Flight build for two days. Is anyone else having similar issues? We tried uploading a completely new app and new versions, checked our certificates and nothing seems to work. How do we solve this?