This morning, I had 2 short walking sessions and, a bit later, a running session.
In the afternoon, I tried to sync my watch with Garmin Connect app on my phone. The 2 walking activities uploaded fine, but the running activity did not.
This is the second time I notice this since updating to FW 14.13. The same happened a couple of days ago.
Again, I had to resort to connecting my FR to my PC and syncing via the Garmin Express.
Before updating to 14.13, I had the same problem with syncing my swimming activities, which, for the moment, seems to have been resolved.