I've gone through the (well done) troubleshooting FAQs and it's important to note the sync once worked a long time ago (many months)
- sync works from windows desktop, 100% and automatic, appears instantly on desktop and mobile
- all other garmin-connect mobile app communication works, weather updates, message alerts, etc. so bluetooth is definitely working
- auto-sync goes through the motions when I get home automatically
- green circle with transfer complete, sync goes through all the motions without errors
- but transfer/sync happens too fast on mobile, activity never appears until I plug it into windows desktop
- the debug audit says there are no files to transfer, like it's seen all the FIT files before, even though there is a new one
it's not a "device not associated with account" problem
thanks for any other ideas