I've gone indoor climbing a handful of times and each time the Total Ascent shows "0". My barometric altimeter works fine. I checked it yesterday by climbing 3 levels of stairs. I get that the altimeter is a bit slow to respond so I've hung out at the top of the indoor climb for a few minutes to let the altimeter acclimate but that didn't work either. I've also verified that there is no water in the sensor hole. Also weather was calm every day that I've been climbing.
Seems to just not be recording elevation change during indoor climbing activity.