sebriviere For what its worth, the AutoFocus on 1ºC change also failed on me the last clear night (night before last), and instead, it was refocusing only by the hour, even though the EAF temperature readout (the ZWO sensor taped to my OTA tube) had changed by well more than the 1ºC when it was triggered by a time change.
I just repeated your experiment, by cooling the ZWO temperature sensor in the freezer and then plugging it into the EAF, and letting room temperature warm it up. After 15ºC worth of temperature change, the autofocus never triggered even once.
@air@zwo could you please ask the developer to recheck the code. Perhaps ask QA to repeat sebriviere's experiment of using ice (or the freezer, in my case). It failed for him, and it failed for me. It will surely fail for your QA, too. I did sebriviere's experiment indoors, and it does not require dark sky, just a dark room and an artificial star in case the process does initiate an autofocus sequence.
The Autofocus routine currently is not accurate enough for my two Petzvals (Tak FSQ-85 and WO WhiteCat51) anyway. It usually ends focusing outside of the critical focus of my telescope (for the FSQ-85, the critical focus region is somewhere between 32 µm and 55 µm depending on whose formula you use). I have been adding a few more fine focusing steps (20 µm at a time on the Tak) while watching the average HFD for multiple stars that is reported by Detect Star function (which is moderately consistent) until it reaches close enough to what I measure at the start of the evening. (This method won't always work if "seeing" deteriorates rapidly and the average HFD increases rapidly. But when seeing is that poor, I give up taking images anyway. It also requires that you don't go to bed :-) With 3 second type exposures, it does not take long to perform. It is a variant of this YouTube video:
https://www.youtube.com/watch?v=HIzqUgWuxOY
By the way, I tried two different sensors and they read within 0.2ºC of one another. I am sure the ∆T is even better. If ZWO can fix the bug, we definitely can depend on the sensor.
Chen