Hi - I just spent an hour with Microsoft via their Chat line on this issue - thought I'd provide you with an update on my experience given your similar one.
I was advised after hours of diagnostics (to no avail) - and no driver updates available on the Surface Dock site that will install on a Surface Pro 8 (but I don't think it would make a difference anyway) - that I should return the Dock 2 to my retailer, and having gone through the rigmarole to do this, I have now used the replacement brand new Surface Dock 2 which exhibits exactly the same problem - there's a problem with the product and how its designed - it wasn't a case of my first one being faulty - they ALL are.
The solution from the Microsoft support person via the Chat support line was to "use your old Surface Dock 1".
They then told me that this issue was not known to them (which I find hard to believe given how much chatter there is regarding this issue) but then in the same breath indicated that the engineers are aware of it and will find a software/firmware solution for the problem.
I honestly don't know what to believe - such an expensive and supposedly premium docking station simply fails to do what it promises to do. I am now left with having to get my money back or just keep it in a drawer until such time as Microsoft acknowledge they have a SERIOUS issue with this Surface Dock 2 and fix its firmware and/or drivers.
In any case, thought you should know.
Good luck with it!
Mike.