2004 Mercedes E-320 Catalytic Converter 'Inc' Code Not Resolved - Smog Test Failure in California

I own a 2004 Mercedes-Benz E-320. The vehicle is displaying a catalytic converter fault code labeled "Inc" (Incomplete). This issue prevents the car from passing smog inspections, which are due in early April in California. This problem was previously reported two years ago. At that time, I received 17 different drive cycle recommendations to resolve the issue. Unfortunately, none of these steps resolved the code. A professional inspection confirmed that the catalytic converter itself is functioning properly and shows no physical damage or failure. Given that the catalytic converter is not malfunctioning but the system still reports an 'Inc' code, I'm seeking advice on what troubleshooting steps or diagnostics are effective for this specific issue in a 2004 Mercedes E-32 or E-320 model.