While processing my latest captures from M104 I encountered an issue during processing with Pixinsight. I never had any issues with the WBPP batch-processing, but with M104 all my frames but one were rejected during the WBPP process. Inspection of the frames didn’t show any issues. I tried everything and in the end I was able to process the frames without the calibration-frames (darks). I have used the calibration frames with multiple other projects without problems. The only thing I could think of was that I updated the camera-driver and shot the “lights” with a different driver as the “darks” which I had taken a couple of months ago. For test I took some new “darks” with the new camera-driver and was able to process M104 without difficulties. So lesson learned: make sure that your “lights” and calibration files (“darks”, “flats” and “flatdarks”) are shot with the same camera-driver!