I'm not seeing problems with the elevation data for my 910XT activities. Can you update the privacy settings and share a link to one of your activities that shows the problem?
the elevation is completely flat as well readings are funny and incorectrec, is it the unit Im wondering? I will just to try give it a good clean as written in one article.
I've seen that before on someone else's file. They had a massive elevation spike (several thousand metres) at the moment the device started recording, probably due to a gps glitch. The rest of the ride was displayed as flat on the graph. You could see the spike only by clicking the elevation graph expand icon. It was solved by cropping the first 10s using strava and reimporting the gpx.
That might explain your improbable elevation. Though in the above case it happened only once, whereas yours seems to be repeating. Dunno.
Would need to look at the file as T.V said or you could analyse it yourself as a csv or gpx to see what the elevation was doing.
