I’m not sure if it is a bug, or a feature request.
I used the TrainerDay App for some workouts and the sync to Strava works great.
I also connected Dropbox to get the TCX Files in a handy folder to upload them to Garmin Connect … but Garmin Connect refused the TCX Files with an error.
When I download the FIT Format from the website everything uploads fine.
So I’m not sure whats easier