Data sink Subreports in the project are not being loaded to custom report of the project

I have a project that has 4 test cases for data driven test and 3 of them has datasink test step that uploads data to subreport which is used in custom report. I can see subreport is being generated but the data is never loaded to custom report when generated. I tried all the ways I can to see how subreports are linked between test step and reporting but I could not figure how it could work. the articles on your portal only mentioned to make sure the step name and datasink subreport parameter should match. I tried it too but nothing worked. I am working on this issue for about 3 weeks and exhausted all ways. Appreciate any help, thank you