I'm having the same issue as above, and just started noticing it this week(first week of Feb-2020) running in a 2018 Tesla Model S on firmware version 2019.40.50.7 with hardware v2.5. After noticing the error message I upgraded to firmware 2020.4.1 yesterday and the problem persists. I submitted a service ticket with Tesla this morning and the rep came back with the following info:
"We have looked into your concern and wanted to let you know this is a known characteristic of the current firmware and will be changed in a future firmware. What is happening the the current firmware doesn't allow remote access to climate controls if the refrigerant drops below a certain pressure. With the cold weather we are experiencing the refrigerant can drop below that pressure and not be an indication of a problem."
To which I responded:
"Ok, that’s logical. One last question. You mentioned the lack of refrigerant pressure is causing the issue. Is it possible I have a slow refrigerant leak, and the current refrigerant level is just low enough to where it causes the pressure to dip below threshold when the car is cold?"
Their follow-up response was that the refrigerant level in my vehicle was not below normal limits, based on the remote data they could gather about the car. I'm not sure if this is everyone's issue or if mine is unique, but thought it was worth sharing. It's also worth noting that I don't have a heated garage for my car and it seems unreasonable to expect that as a prerequisite environmental requirement in order to preheat the battery for winter driving, especially since the car will likely be parked outside in a non-climate-controlled area when I drive to work, store, or anywhere away from home. The rep went on to say that the issue "should" be fixed in firmware v2020.8