Thermostat card - Set Point transitions

I have built my own thermostats, and think I am sending all the correct info, but not so sure now.

Is the card supposed to transition from a single setpoint for Heat and Cooling modes to a double setpoint (min/max) for auto or heat_cool modes? …and back again automatically?

if I start everything in either ‘heat’ or ‘cool’ modes while only sending content for the ‘temperature_state_topic’ then I correctly see one temperature setting on the card. When I change to ‘heat_cool’ mode and start sending the two temps on both the ‘temperature_low_state_topic’ and ‘temperature_high_state_topic’ (and stop sending ‘temperature_state_topic’) the card changes to two temp settings as expected. BUT… if I change back to ‘heat’ or ‘cool’ and change back to the single ‘temperature_state_topic’ the card continues to show two settings.

What is the trigger used by the card to transition?
I’m sure I am missing something simple here, but can not find it.

Thanks in advance…