I've used Wahoo Element Bold device to record this activity https://connect.garmin.com/modern/activity/2484130689 which I uploaded as .gpx file. Why is there no Training Effect score calculated? Shouldn't HR data be enough?
No. For starters, it isn't really a technical question but a commercial one. I don't think Garmin has acquired a licence from Firstbeat to use the Training Effect algorithm in the cloud-based Garmin Connect service, and in turn you never acquired a licence or right to apply the algorithm in the analysis of any data you upload; only what your Training Effect equipped Garmin device model recorded will be used for the TE calculations performed on that device, which is then sent as part of the timed activity record to GC upon syncing, and GC only reports verbatim what it was told. It's not a question of what is technically possible or what would be desirable from the user's perspective, but what you have (or haven't) paid for.
