I think that the algorithm that changes from baro to alti mode automatically is not doing its job good enough. I have no way of knowing this for sure, but my guess is that it’s not the same algorithm that is used in other watches. I had much better results outside of activity with Suunto 9 Peak, Suunto 9 baro and ambit3 peak.
I wear my Race 24/7 and almost every morning I see altitude almost 50m more than the night before. During the activity, it’s very good, altitude is mostly spot on, but I have also seen crazy ascent values (like more than 50% more) few times (but that is not so uncommon with Suunto watches I guess).