Some completed rides not uploading to Garmin Connect

Some of my rides are not syncing automatically to Garmin Connect.

When I tried to download the TCX or FIT files from Trainerday to upload them manually to Garmin, it gives me a message saying: “An error occurred with your upload. Please try again.”

Please advise.

Can you send me an example of what that fails? Sounds like a bug of some sort. You can send it to