My issue is fixed!
History:
-I've had this issue since I got the devices in December.
-Chatted with Microsoft support. They swore it was the dock itself and sent me a knew one. Same issue with the new one.
-Last week I did TWO things and one of them seems to have fixed it. 1) I ran "Method 1" solution from the below Microsoft Answers thread. 2) I ran the 2/17 updates Windows and Surface firmware updates.
I don't know which of the two items fixed it. If it was item 2 I don't know if the issue was related to Surface firmware or a broader Windows 10 issue. But the bottom line is that this was an almost daily issue for me. SO frustrating! Now both docks have been working flawlessly for over a week. Such a relief! Going forward, Microsoft has to do better debugging these things BEFORE they become available for sale, but props to them for at least staying with it and fixing this. I'm sure they're learning from it.