I found a bug in the visualisation of a Backcountry Skiing Activity once it has multiple segments.
On Garmin Connect Web it displays the multiple segments (Uphill - Downhill - Uphill - Downhill) in the correct order, not on Connect Mobile iOS:
Connect Web - Altitude Profile:

Connect Web - Segments/Splits:

Connect Mobile iOS - Altitude Profile:

Connect Mobile iOS - Segments/Splits:

It is also reflected wrong in the GPS recording / Track visualisation.