Can a negative Min Elevation be avoided?

Do you have auto calibration enabled?

IMO that is a pretty nice elevation chart and, assuming the DEMS calibration is correct and you are actually running down to sea level, I'm only seeing a very small drift downwards throughout the intervals (and that is over a couple of hours - it looks like about 1/2% variation between total ascent and descent). The elevation change of each lap looks really close (can only tell so much from the graph) and look to have peaks and valleys closely drifting down.  If you are using auto calibration then I would still say that is pretty good considering any weather changes throughout the run and auto calibration can cause some jumps.  You can try playing with settings but keep in mind what will work on one run may not be as successful on another.  You can generally expect some drift so starting at the bottom won't likely change anything given the drift can go either way and, technically, a higher max elevation is still just as wrong as a lower min elevation - it's just that the minus number stands out more.

#Matthias# said:

Do you have auto calibration enabled?

No. Does it help to have it enabled?

I have seen the oppossite happening with the Fenix 3HR. The elevation graph would creep upwards towards the end part of the workout whereas on the Fenix 7x it has a tendency to creep downwards. Not using Auto Calibration.

Yes, auto calibration should help in that scenario. The altimeter uses ambient air pressure to determine the elevation, but air pressure also changes naturally with the weather. Therefore a drift is quite normal. Auto calibration does frequent DEM calibrations during your activity to reduce such drifts. 

But if care about total ascent you should not use auto calibration…

Unfortunately we no long have a pure and straight option “calibrate at the activity start” …

All current options are confusing with words like “might” “if” etc …

marcossaad_ said:

Unfortunately we no long have a pure and straight option “calibrate at the activity start”

Would manual DEM calibration at the start of activity not yield the same result?

marcossaad_ said:

All current options are confusing with words like “might” “if” etc …

I don't think it is confusing: 

Auto calibration "On": Auto calibrate over night and also constantly during activities 

Auto calibration "nightly": auto calibrate over night and only prompt for (optional) manual DEM calibration at activity start.