I had an opportunity to use a QHY5lll 462C planetary camera the other night. It works well for capture and live view works fine. However there is a major issues with SER recording. After the recording stops the camera is put into a state waiting for the buffer to offload and save the recording. I gave it a lengthy amount of time to finish, but it never saved the file or became responsive.
Running Raspbian Buster 65bit, Pi 4 8GB with SSD system drive. KStars 3.5.5 Beta, recently self compiled.