Hi,
After the upgrade of my Fenix 5x plus to 8.40 firmware, my pace, and the distance in consequence, is too way off on a treadmill running. It seems that this upgrade wipe out the calibration that I done before.
It was a 6k running and the watch showed 7.75k (I do not use a foot pod)! Before the upgrade the error in my treadmill runs was in the order of +/-150 m.
Another issue to mention is that the battery has drained 2% (too fast in my opnion) in 45 min of activity (6k treadmill running and strenth workout) without GPS or Music, only sync with the phone and the RD pod.