@tnick STM32F1 2019.12.8 (stm32duino) is the version that was active when the latest MySensors release was made. Later versions may or may not work; nobody would know until they tried.
I'm having the same / a simular issue of temperature related readings, but at a different temperature level (for me it must be > 14 degree). I massure the dew point as well (temperature = orange, dew point = yellow). It looks to be more related to water in the air than only to temperature.
@zboblamont have you been finally been able to find a solution?
Update and problem fixed!
For everybody that will encouter this, the problem was at the sensor side because of the folder of the sensor! We created some metal brackets for it and they where exactly the same diameter. The fact that the mount squeezed the sensor made it return the lowest value.
Just needed to adjust the hole and everything was ok!
