Manual Sync on Fenix 6X, via WiFi, says that it has failed, however on site it appears to have uploaded all data. I first noticed this on July 5th. Is this a bug with updated software? It finds WiFi, goes into sync mode, then says that it failed every time. I tested it by sitting in front of the Garmin Connect site on the Sleep tracking page. Did a (failed) sync, refreshed the page, and the last sync time corresponded with the time of the failure.
I've had the watch for a few weeks now and had never gotten a failed sync message, although sometimes it took a bit longer than others.