I am having a similar issue, my hierarchy is the following: I have a DC, SQL and SCCM (3 servers in total).
I installed the Reporting Service Point in the SQL server. When I tried to see the default reports on the console it says no items found. This is the strange part of the issue... if I go to the SQL server and go to https://sqlserver/reportsI am able to see the configmgr folder, run the reports, and all the permissions are set correctly, but if I go to the SCCM server and try to browse for https://sqlserver/Reports it gives the not available page error.
Any idea what could it be?