No, I did not open a ticket. That was gong to be my next step, but I've found a workaround.
To bring up to date - I have been operating under the impression (determined early on in this thread) that this error was a false positive. I discovered a couple of days ago that this is not the case. When I have a DC in a failed poll state, it is not collecting login information. I had 2 DCs that had been in a failed poll state for 2 weeks. I verified the last logon record for that domain in the Orion database was 2 weeks old.
Workaround - In the past, I've been deleting and then re-creating the node. Then I found something that's been in front of my face the whole time. There is a way to manually force a poll. Go to Settings --> UDT Settings --> View UDT Job Status. Find the failed DC and click the Poll Now button. Immediate relief.
Some History - In earlier versions of UDT when you went to UDT Settings --> Manage Active Directory Domain Controller, it automatically forced a poll of all managed DCs. I found some entries in this forum complaining that this was a real pain in cases where many DCs were managed. There were requests to stop this behavior and replace it with a manual alternative. Apparently the Orion/UDT team was listening and this is the result. So on one side this is a good thing, but obviously the scheduled polling shouldn't be failing and must be addressed. I'm sure they're monitoring this thread, but opening a ticket may be the best way to ensure a fix is in the works.
Jay