@tech@zwo#48214 I think I have it figured out.
When it wasn't working in the dark, connected to my telescope, I brought everything inside to do some testing.
Outside, I was connected to the POWER CABLE, that I assumed was only needed for cooling. I was also using the included ZWO USB 3 cable that came with the camera, also connected to a USB extension cable, into my computer.
I was getting the message in APT about Waiting for image from camera, and the photos wouldn't load. This also backed up my APT plan and after 2 hours I only had the first photo and nothing else.
As I started doing test images and test plans in APT, this is when the camera would disconnect and reconnect. Under 2 seconds, it seemed to work, but anything longer would not work.
I tried all of the three USB ports on my computer and got the same bad result.
This is when I came inside to do some testing. Now, I'm using the included ZWO USB 3 cable but NOT the power cord, because I assumed it was only needed for cooling. I got the same bad results.
This morning, I plugged in the power cable to the camera, and the induced ZWO USB 3 cable from the camera directly into my computer - and it worked.
Of course I got confirmation, with my USB extension cable, even the USB to the USB-C adapter gave the BAD result, in all three USB ports on my computer.
ASI2600 Plugged in to power adapter and using the ZWO USB 3 cable is working perfectly in my office (not connected to telescope), and I was able to run a plan in ASIstudio and in APT that included 300s subs with no problems.
I will test in the dark, connected to my telescope soon.