Welcome back, Bob. I hope you enjoyed your family visit.
I now believe the camera is defective, and I am in email contact with an engineer at ZWO in China. He asked me to run a few tests, which I did yesterday.
MaxIm downloads images fine at ambient temperature, at 0C, and at -20C. The problem occurs after a 180-degree camera rotation at -20C (only). It does not occur after rotating with the sensor at 0C or ambient temperature -- only at -20C.
The mount is parked and powered-off, and ACP is not running -- just MaxIm alone.
After looping and tying-down all cables to the camera, there is no chance that rotating the camera puts any strain on any cable connected to the camera.
I suspect (and so does the ZWO engineer) that there could be a cold solder joint inside the camera. He wants me to do one more test using ZWO's ASICap imaging software, and tapping the camera when cooled to -20C vs. rotating it. I will do that tonight or tomorrow when the rain quits. I also will do this same test with MaxIm, since that's where the problem occurs, and is the program I must use with ACP.
Another part of the problem is that sometimes, when MaxIm does download an image, it is the previous image! Yesterday, I was imaging my light box when the problem occurred. I switched the light off and on during the 1-second exposures. After each exposure, MaxIm displayed "Reading" for 8 seconds, then downloaded the same light-on image every time. Very strange.
The camera has a 2-year warranty (bought new in July), and ZWO has been quite responsive. They even asked me where I bought it. Sounds like they're planning for an exchange.
Is there a way to set this mode within MaxIm, independent of ACP? Might be worth a try.
--- Mike