One unit is refusing to keep a schedule in the thermostat, thus leaving air conditioning on 1 temperature all the time.

This lowers the inside temperature significantly.

The water temperature today in Miami is 71 degrees.I was in Boca Raton, Fl.

Simply put, induction is turbo-charged cooking.Like gas cooking, induction allows for instantaneous and precise temperature control, which makes it as responsive as gas.

There are models of ductless splits capable of functioning down to -20C (-4F) ... yes their efficiency diminishes as the temperature drops, but it still beats heating with EBB alone.

So for example, if you said, please smoke outside unless it is really cold, then you could quite easily notice that the temperature threshold which constitutes "really cold" could start drifting upward over time.

Notating the pressures/temperatures of the area and unit, whether they changed the run/start caps, checked wiring, cleaned coils, and how, etc.

Theoretically, you could disable the minisplits during the winter, so that they cannot be used for heating, and use a "dummy" thermostat in a prominent place, and have the real thermostat, set to 68, in a hidden place that they cannot access, but that reflects the temperature of the unit. 

Because there is overwhelming observable and measurable evidence that shows without a doubt we are in a time period of increasing ocean and land temperatures; changing weather patterns and increased frequency and intensity of events such as hurricanes, hail storms, wind events, flooding and wildfires; changing biosphere patterns; accelerating glacial melting at the poles and extreme northern and southern latitudes; and rising sea level just to name a few.

Have you checked the actual temperature in the unit?