FAS is a valid method of logging into the the Red Hat Bugzilla for Fedora. However, you cannot use your FAS credentials to login to Bugzilla to submit a problem report in the Problem Reporting application. Is it possible for Fedora Infrastructure and the developers of Problem Reporting to address this, or is there a blocking issue or organizational block?
The What Can I do with my Fedora Account (FAS)? article notes that you can login to Bugzilla with your FAS, but doesn’t warn or note that this does not include the Problem Reporting application and process.