Fields Avg/Max Descent; Avg/Max Ascent do not appear to be working for Skiing?

There are 4 fields, Avg Descent, Max Descent, Avg Ascent, Max Ascent. I put them on a watch face for activity = Skiing. They all remained at 0 during the entire activity.

The manual states that they are The average [/max] descent[/ascent] rate since the last reset. Do these fields work for others? Does anybody have an explanation as to why they remained at 0 during the entire activity?

Also, slightly curious to me, all these fields have an upward pointing arrow, whether they say "descent" or "ascent". Can anybody explain why the arrow points upward for both ascent and descent?

Thanks!