As a mountaineer, I have also missed this feature terribly. But I am also a developer and programmed a solution myself: VSPD Vertical Speed.
VSPD Vertical Speed is available for download in the Garmin Connect IQ Store. Please note that it is still in development. So if you have problems contact the developer. If you like it write a positive review.
VSPD is based on the Barometric Sensor. The altitude of the GPS has proven to be unreliable in the mountains. The problem is that the barometric sensor has a lot of noise. When smoothing you lose the reaction time. That's probably the reason why Garim Vertical Speed only shows 50m/h (which is too inaccurate for my use in training.
Check it out and let me know what you experience. By the way, Garmin's presentation of the count also has flaws. Negative values are not always colored correctly. Blame Garmin for that not me.
