I have had the 920XT since about Feb 2017 and it has been connecting fine until yesterday.
First issue is that I could not sync through wifi to post my workout. The settings on the iphone indicated it was connected, but Garmin Connect on my phone will not sync.
I get the message "Your device seems to be busy, and your sync request timed out. Try again later."
When I connect the 920 to my Macbook, Garmin Express does not recognize it, and I eventually get the message "The disk inserted was not readable by this computer".
Following steps to run first aid did not help.