I have an answer from the Honda technician. Likely
THE answer to my Remote Climate issue.
It turns out the car has particular conditions under which it will decide to cool or heat the car using Remote Climate either on the key fob or HondaLink. The car has a temperature band it calls the "Comfortable Air Temperature Zone." If within that zone the car will not heat nor cool in Remote Climate mode. The technician was able to pull up a few pertinent pages on his laptop (after 1/2 hour of searching). He's printed the pages and I scanned them in as a jpg file - attached. Perhaps this data is in a service manual. It should be in the Owner's Manual in my opinion.
Our winters are mild here, and the car is kept in the garage. The conditions to heat the car with Remote Climate are the ambient temperature in the garage must be 77F or less while the inside of the car must be 59F or less. Otherwise the heat won't come on. It does seem possible that our car didn't fall under those conditions, but 77F in the garage in winter! Well it gives me a ton more information. I will now test the car in the wee hours of the morning to see if this data solves the problem. This chart also explains why the Remote Climate system did work one time when the conditions must have been just right.
For those who have a Clarity and report that the Remote Climate works I'm guessing you are in much colder climates than we are. At the moment (Dec 27) it is 57F. The garage is 62 and the inside of the car is 69; so the heat would not come on according to the chart.