I think I’ve found a bug.
It seems that if you view a history graph of a thermostat entity, if that thermostat changes modes from heating, to heat and cool, the history graph will stop showing the set temperature in favor of the new heat/cool set temperatures. In fact, even after switching back to exclusive heat mode (or even exclusive cool mode), it will continue to only show the heat/cool temps until the time window that the graph is displaying no longer has any reading for the heat/cool temperatures, before it’ll start showing the set temperature value again.
Is this purposeful, or is this a bug?
I’d expect any history graph to show all available data, when there is data within the timeframe selected.