Garmin Connect didn`t import the cadance from my gpsmap64s activity

PS: I tried to remove the gps unit from my Garmin account, but also from the phone. Then I synced them again: nothing. Same thing. In Garmin Connect, all the graphs appear except for the cadence.

Did you verify that the Cadence graph is not just disabled?

If it is on, or not available, then please make one of your activities public, and share the link to it here.

It is not available. 

I will send two links. In the first one you will clearly see the cadence graph. In the second one you will find only the maximum and average cadence index, without a graph. The two activities represent the last activity with cadence and the first activity in which Garmin Connect no longer displayed the cadence graph.

Last activity with cadence : https://connect.garmin.com/modern/activity/9923242141

First activity without candece: https://connect.garmin.com/modern/activity/10002683241

10xs!

I even thought of analyzing the gpx files that come out of gpsmap64s and the one that I export from Garmin Connect, of the same activity. The gpx file exported by gpsmap64s contains the cadence, the file exported by Garmin Connect after synchronization with gpsmap64s no longer contains the cadence. So I think the problem is with the Garmin Connect application, which no longer accepts the cadence from gpsmap64s.

Yes, it looks you are right, and that Garmin Connect indeed stopped importing the cadence from the GPX files. I checked both activities, and also the JSON data hidden in the background - the older activity has the cadence data included, while the newer one does not. It only has the totals (max, avg cadence).

You can try importing the original GPX files manually at https://connect.garmin.com/modern/import-data, to see whether it makes any difference. Otherwise, all  I can recommend, is disabling the auto-updates of Garmin Connect, and installing an older version of the app from apkmirror.com. However, if the import in GC Web does not work ether, now, then it is quite possible the change was made on Garmin's servers, and that the downgrade to an older GC app version won't change the behavior. Worth of testing anyway.

The problem is that no Garmin devices use the GPX files for storing activity data since many, many years, and hence it is not very likely Garmin will assign any resources to fixing the issue.