I’ve just done an Ironman with my Elemnt Rival. Not only I cannot edit the transitions as the app is supposed to do, but they syncronized with Strava, everything except for the swimming. Weird enough! I have a Samsung Galaxy S21 Ultra, not sure that is the problem.
Here I leave some captures (in spanish though) to get some help.
I had a similar issue over the last week with different types of activities although they weren’t syncing at all. I had to deauthorize Strava (profile > authorized apps > Strava > deauthorize) and then authorize it again. Voila!