For all of you ASI2600MC-Pro users who have been experiencing issues taking exposures or downloading images from your camera, the attached test report may be of interest to you.
I ran some tests with my ASI2600MC-Pro and measured current draw on the USB interface and the 12VDC power input jack. It's important to note that in spite of what the ZWO manual states, you absolutely MUST connect the 12VDC power supply for the camera to be able to take images and download them reliably.
Separately (but not unrelated), some people recommend using USB 2.0 cables for higher reliability at the cost of somewhat slower image download speeds. ZWO strongly recommends using USB 3.0 cables to connect to the camera, and that's what I do. But it can be tricky - I have one 3m cable that is rock-solid reliable, so I bought a 2nd one of the exact same type as a spare and my laptop doesn't even see the camera when I use it. I also have a triple-shielded 0.6m cable that doesn't work at all, while a 1m version of that same cable from the same manufacturer works flawlessly. So in my experience, using a high quality cable helps, but is no guarantee - it's very "hit-or-miss". But in general, I agree with some of the suggestions made in other threads - keep the cable short, don't use USB hubs (connect directly to the camera), and try different cables until you find a couple that work (and always bring a spare).