I've reached out to support a few times with no response, so I'm trying here too.

I was a long time Nike Run Club user, and I recently got a Coros watch. In trying to get my historical data from NRC to upload to Coros, I was unable to obtain .fit files from NRC. The data must be in .fit for Coros to accept it and populate prior activities. I've only been able to obtain the data in .tcx, a format per Coros that wont work, even though their upload page says it will.

That brings me to Strava - I signed up and entered all my NRC data into Strava, hoping it would sync with Coros. Unfortunately, it seems Coros doesn't "back-populate" the old activites, only new ones in Strava. I see that on new activities, I can export one-by-one as .fit files, but those are already synced from Coros to Strava. 

I'm really hoping I can get Strava to export the prior acivites I manually entered as .fit files or find help in converting my NRC and Strava .tcx exports to .fit, so I can have a full history in Coros.

Any help would be MEGA appreciated!!!