Power BI Report Server on Custom Authentication wont load reports in iOS app.

I have an instance of Power BI Report Server with the Custom Authentication feature enabled. Reports look great on the Report Server, but when I go to open a report in the app I am stuck in an endless spinning wheel.  I can refresh the server and see new reports I've added / removed so it is not a general connection issue.  I feel like it's getting stuck on the custom auth, but if that we're the case how come I can see new reports I've just added and there is no issue with refreshing the report list.

Curious if anyone with Power BI Report Server + Custom Auth has had any issues with the iOS app.

Thanks,