PCTV 461e works fine in NAS but terrible picture on KIII Pro with CoreELEC 9.0

I have a Synology NAS (DS1815+) that I had my PCTV 461e DVB-S2 USB stick plugged into. I was using TvHeadend with it and the picture was always fine. I decided to move the 461e to my KIII Pro as a secondary DVB-S2 tuner but the picture is terrible. Its all broken up and TVHeadend reports lots of continuity errors. If I remove the stick and plug it back into my NAS it works correctly again. If I swap the cable with the DVB-S2 tuner builtin to the KIII Pro the picture is still bad and the continuity errors are still present so it seems to be CoreELEC itself or at least the driver that it used. In both cases the NAS and the KIII Pro detect the 461e as a Montage M88DS3103. I also have a PCTV 292e and I am using the CrazyCat drivers.

Has anyone else experienced this and is there a fix? Is there a way I can migrate the fw for the “Montage” from my NAS (x86) to the KIII Pro (S912)?

Thanks guys

Is this a known issue? If so thats fine but I would like to know for sure. Thanks

Alternatively is it possible to add fw files myself? I know this is difficult with parts of the file system being read only. Is there somewhere I can put this to test?

I use a very old DVB-T stick and I have no problem. My stick is connected to an external USB 3.0 hub with its own independent power so as not to overload Mecool KIII Pro.