The reporterdiags.zip file can also be created while Reporter is not running. Navigate to the root of your Reporter installation (the default root install folder is /opt/bc/reporter/) and run:
./bcrdiagnostics
To be more specific, you can also run:
./opt/bc/reporter/bcrdiagnostics
Enter in your SR number and press return. If your server does not have direct Internet access, the upload fails but the zip file generates in the root install directory.