Error in fiddler - flighting is not enabled for domain ..oauth not_available

Windows 10

Outlook 2013

Tenant provisioned a month ago

Registry keys have been added to support modern auth in outlook 2013. Autodiscover SCP registry key has also been added.

Users are synced from On prem (No exchange attributes synced)

Mailboxes are being migrated as PSTs

FOr all domains in 365, when configuring the outlook profile, it throws an error "flighting is not enabled for domain oauth not_available" while authenticating and autodiscover fails.

To test, I recently added a new domain to my tenant and i get O365 authentication prompt and works fine.

Tried on multiple computers with office 2013 installed and encountered the same problem.