“When you say unstable, in what regard ? under what circumstances ? Most temp sensors are very slow responding anyway, so naturally damp out things.”

It jumps around +/- 3-4 degrees but this is enough to switch the fan erratically.
I have always thought It was “noise” but can’t see a filter in the Maxx to dampen it.
This is what lead me to wanting to move the sensor, but think your correct in that the sensor can’t respond that quickly.

Back to the drawing board. 🥴