I'm in the western Chicago suburbs, and I have a basic SD DTA in the bedroom. I have noticed that it's channel map has not been automatically updated for awhile, and some channels are no longer working. My main cable box is fine. I ended up rebooting the DTA, and it finally updated it's map. In the past, channel changes typically occured automatically.
Before the reboot, the issues were:
CLTV (53) and FM (140) were still in the map and you could change to them, but of course get an error that the signal was interrupted.
Several channels were tuning to the wrong frequency when comparing the diagnostics between the DTA and main cable box.
Thanks for this good report of what you observed - it sure can help other readers and viewers in your area especially. The issue you observed is not necessarily unusual but probably a mistake too - someone forgot to click "yes" at comcast. You took the right step to try to fix the issue yourself and if I was comcast i would credit your account $10 since you probably saved comcast $14.47 by not calling tech support about it.