You can migrate existing reports from your SQL Server Reporting Services to Power BI Report Server with minimal effort for native mode at least:
1. Backup existing SQL Server Reporting Services (SSRS) Database
2. Install the Power BI Reporting Server
3. Restore Reporting Server Databases to Power BI report server instance
4. Connect to Reporting Server Databases using the Report Server Configuration Manager.
I have the same issues. I was connecting to SSRS server and when I noticed report was stale and not refreshing I tried logging out and now I cannot connect anymore. This is an issue with IOS. It works perfectly on my Android phone.