If you have an ACP run log, you can see the binning that is chosen. It is based on your focal length, and tries to get to 4"/pixel. It will be 2, 3, or 4. This discussion has wandered all over the place :-) This conversation is all over the place. Recently we've found that at least one ZWO camera is being shipped with a default bias/offset that results in a huge black-level pedestal, with bin-4 completely failing due to all pixels being max white ("black" level 65536). Try setting your offset/bias to 1 or 2 and see if the solving problem goes away. However I am running on almost no real information here. I suspect there are several unrelated problems that are being conflated.