AFAIK my darks and bias masters are fine. In fact when I use them with other subs, it works just fine. Although I was experimenting with different gains and offsets, I used 139/21, which is the same values used in my darks, flats, and bias frames, in case that may have anything to do with it. I think I may have used the ZWO driver for my subs, whereas I used the ASCOM ASI driver in the past. Any chance that would make a difference? I'm using a 1600 mono cooled.