Hi - I have a very similar camera, the QHY247C. A few ideas:
Is the 12V power cable secure? I had issues with a simple push-on DC connector being intermittent and went and made up cables with the screw-fixing version. I wrapped it around a ferrite RF choke for good measure.
It might be a grounding issue, or loop. There is some mention of this on QHY site. All my power supplies have their 0V lines tied to a common point. Cables are bundled to avoid loops too.
It still might be a USB traffic setting issue in the ASCOM driver even though you had issues with it just sitting there. I found the default USB traffic settings on my QHY guide and capture cameras were all too optimistic. I changed them and have had no further issues. If I recall correctly, you increase the slider to make it more reliable.
Other interference can be caused between USB3 and WiFi. While it is possible to use USB3 with this camera, I use USB2 with the QHY247C as the download time is still tiny compared to the imaging exposures.
Lastly - the old recurring problems of USB hubs. Some hubs are simply not up to the task of working outdoors and often show their weakness as the weather gets colder. Several friends had issues, all of which were solved by loaning them my spare hub. I use an industrial grade hub that has ESD protection and works at cold temperatures.