I have imported all of my older Garmin activities using the Link to my Garmin History File.
For these older activities, there is no Hyperlink to the activity on GC, while the Link to Strava is working.
Is it possible to read the Garmin Activity Number from the activities in the Garmin History File to also create the link to Garmin Connect? I guess this number, which is also in the name of the fit file when downloading directly from GC, is the only necessary information needed for the hyperlink.
When I did the original import code I couldn’t find any way to get the GC id’s for the activities. Even matching activity summary info to the fit files had to be done with heuristics. No direct link. That said I might have missed something.
Maybe you could re-request your data from Garmin and have a look at it? Specifically see if you can find any way to get the GC ID for that activity.