First time I'm seeing this in my many many years of owning a Garmin Forerunner watch (currently 935)
"They sync for your Forerunner 935 device was successful, but it will take some time to process the data."
Sure, okay, but my run shows up on the app, not my steps. My run is in GarminConnect web and has synced to Strava etc, but not my steps.
However, my steps recorded AFTER my run are syncing, my watch shows 8883 steps right now but GC app shows 579 and web shows 269!
I wear a Lily when not running, that's showing 579 steps, but my Forerunner 8883 - it is syncing with my Lily as there were only 8502 steps when I finished my run.
So the data is syncing/flowing/processing, but only some date only to some devices/services and only for certain blocks of time!