Few weeks ago (not sure if this is related to latest software update or not) my Fenix 5X+ stop synchronizing steps count with Garmin connect.
On device itself I see all the steps for every day and the seems to be Ok. But in Connect data is not full: device stop syncing data for previous days. For example if I didn't sync device at all during the day I've got 0 steps. If I sync it with some steps and than add some and sync them next day they are not appearing in Connect.
I'm using latest Express on Windows.
With same Express on same Windows 5S+ don't have this issue.
Support is sending me manuals how to connect device to my PC, so they are useless and terrible.