We are experiencing an issue as well. If you attempt to add a build for submission, the controls are all broken in the resulting pop-up. The top of the pop-up reads:
{{ l10n.interpolate('ITC.AppVersion.BuildModal.Title') }}
The same is true with the TestFlight tab. Under Internal Testing, nothing works. All the controls on the screen are broken. The top of the screen reads:
loc('ITC.apps.testinformation.internalTesting.title')
And if we try to view the TestFlight Builds -> iOS option, it just loads indefinitely. The loading circle animation is the only thing that appears.
This all started yesterday, Nov. 5th at 8:00pm (pst).
UPDATE: I have spoken with Apple developer support and submitted a ticket as of Nov 6th at 8:30am. It appears that the Users and Roles feature is also broken in iTunesConnect. It too sits at a loading screen indefinitely.