How to verify Data source credentials on service for Read only node

The IT team has instructed me to use the secondary node for my PowerBI reports and the node is set to Read-Only. This was previously set to read/write and I had created my report, uploaded it to the service and scheduled my refreshes. A few days back it was set to Read-Only and I am reporting off this by setting the 'Enable SQL Server Failover support' to true to get the Read-Only string in my connection     .(I am not sure if this is the correct way to connect but this is what we could settle on given the time and workload)

Now when I upload the report on premise after the Read-Only setting, I am unable to verify Data Source credentials. The report is working fine on premise and is also updating on the previously set schedule, however, I am unable to change the refresh time as the scheduled refresh section is all greyed out.

Any reason why I am not able to verify it but the report is working all fine. How do I fix this?

Let me know if you need any additional information.