Full vs partial Strava Xert updates

Some (non-Xert) rides with a breakthrough get updated in Strava to something like “Difficult Mixed Puncheur Effort - Xert”, together with detailed stats (fat/carbs/difficulty) in the description and a breakthrough graph.

Others just turn into “Evening Ride - Xert” and with BREAKTHROUGH in the description, but nothing else.

I’ve seen some hints that this is due to Strava vs Connect syncing first, and Xerts’ ability to update the ride (http://baronbiosys.com/frequently-asked-questions/#collapse-1-6032), but that doesn’t entirely make sense: in both cases Xert is updating the ride’s title and description. Just for some reason, sometimes it does a small update, and in other cases a big one.