Our engineering team mentioned that wireshark capture on mX mXP module (Landslide of TestCenter Platform) is not supported when "Use TestCenter Data" is enabled. This is because the Spirent TestCenter FPGAs are handling data in this scenario and there is currently no way to capture packets since Spirent TestCenter does not support this for Landslide. If you are using traditional Landslide data (Use TestCenter Data is disabled), the Capture functionality should work as usual.