@lunarchickadee We’ll probably need some images and more specifics to be sure, but some reports require parameters to be filled in to populate data, so if you’re strictly working out of Report Designer you’ll need to account for that and put them in via the build schema to test the data output.
Same thing with the subreports, some can get report data transferred to it, but some require a parameter entered on the main report to get passed to the subreport. Typically when working with subreports I will add the subreport as a separate report to the site and test it individually, then once I know it’s working as expected and the correct data is shown I’ll incorporate it into the main report and verify it’s working. If it isn’t then usually this means something is off with the connection or something is not being fed to the subreport correctly, but I know that the subreport itself is ok.
Hope this helps but if not, please provide some specific examples