The issue has been resolved. New users are now able to connect new iTunes Connect Data Sources and the existing Data Sources will now continue syncing as expected.
The issue was caused because the iTunesConnect’s login link was changed which prevented us from accessing their API.
Posted Nov 20, 2019 - 02:52 EST
Investigating
We are experiencing syncing delays for iTunes Connect Data Sources and Custom Metrics. Connecting new iTunes Connect Data Sources is not possible.