There is a lot of discussion about this if you use search.
The summary is that the bed being on messes up the sensor.
Best alternative is to heat bed to 5-10º above printing temp and then run calibration. With carryover it will be close enough.
No need to heat the nozzle.
-S
Thank you for that - but if the heated bed messes up the sensor, should the bed be cold?
I’m not compelled to heat it up. My goal is to find a reasonably consistent method to get acceptable prints. Thermistor, leveling, tramming, warping, temperature, and filament quality. I’m sure there are others.
If leaving them cold is better, I’ll try that again.