Not sure if this is related but I determined that I needed to turn off MaxIm's threading options on the camera setup. These settings created all kinds of lock ups and crashes. There are other things the ZWO ASCOM driver doesn't do well in MaxIm... e.g. I found I cannot open the Camera Settings in the camera-1 tab. If I do, nothing happens (no settings dialog comes up). ...but then not too much later MaxIm DL will crash. The MaxIm DL folks say this an issue with the ZWO ASCOM drivers. Lastly, I started plugging my guide camera directly into the computer rather than thru the 6200MM's hub. I might try going back into the hub just to see if that is still an issue now that I've turned threading off. So, in summary: 1) turn threading off, 2) never press the Settings button the camera-1 tab, 3) possibly plug your guide camera into the computer and not the 6200MM's hub.