When you say
Does this mean you see this exception after upgrading to a newer version or that SGPro is unchanged and it started happening all of a sudden?
We saw something similar years ago here:
We made the changes that @Chris suggested. Not really sure why this pops up… maybe somebody else has seen this? It never usually fixes anything, but you might try to uninstall ASCOM, download the latest and reinstall. I see your tests passed, but there is no guarantee of test coverage for this particular issue.