I heard back from ZWO about this. Sounds like an incompatible combination of how their drivers handle temperature changes and how the Cool Down works in SGP. Essentially, I believe that you’ll need to disable the cool down option in SGP or have the time set to be 0 minutes.
When using the SDK the driver will not increase the power to the cooler if the new set temperature is very close to the existing temperature (I’m not sure what “close” actually means…but likely a couple of degrees to prevent wild spikes in power while attempting to stabilize the camera).
I have not seen this with my ASI1600 but they mentioned that they did replicate the same behavior with the 1600, so I’ll give that a shot again. Maybe because mine is the older “non-Pro”?