Symptoms

Unable to enter the correct SQL Reporting Services configuration when running K2 blackpearl setup in Modify mode
 

Diagnoses

When running setup in Configure mode, we have correctly set the SQL Reporting Services URL. When we run in Modify mode to install client tools, the SQL Reporting Dropdown list does not contain the correct URL, as shown in the 3rd screen shot below. This was discovered when reinstalling client tools on the server.
 

Resolution

We ended up removing K2 and uninstalling Visual Studio. K2 for Reporting Services was installed in the SQL Server and in K2. After performing this actions we were able to install the client tools and select the proper Reporting Server from the drop down list.