Mock Server with OPA5 testing does not work

Hello folks,

I am working on OPA5 test scripts for a UI5 app with smart controls. When I try to load the app in frame via iStartMyAppInAFrame("../../index.html?responderOn=true"), mockserver is not considered. Instead, service calls are referred to the server. I could not find any additonal steps in the documention. Linked question OPA - Mockserver states same problem and mentions about injecting the code, but could not figure that out either. What is it that I am missing? Can you please help with your inputs.