I had a look through the wiki and the user guide but didn't see much info - and the answer could simply by "garmin changed".
When exporting to TCX and manually uploading to
connect.garmin.com the activity is showing a blank, absent or 0 value for time, distance and calories.
Once in garmin connect I can manually add those in and everything then looks fine.
I will have to wait till I get home to upload the json and tcx export file.
Using GC 3.4 on mac.