Hey @Gubrist,

If you aren't seeing your activities synced, could you try exporting the activities from Decathlon then uploading to Strava manually? If your device can export or record activities in GPX, TCX, or FIT format, and these files contain actual workout data, you can upload the files here.
 

More information on uploading manual files can be found here.
Additionally. here is a link that reviews getting activities into Strava.

Thanks.

One single activity of total five has been transferred to Strava.

Import a GPX File to Strava would require the PC and the Web-Version.

I want to use my Smartphone on my sport vacation only.

So I wonder why not all activities have been / are transferred to Stava.

I'm having an issue here too.

Only activities that I started after I setup the Strava sync are being synced.

The one I completed 2 minutes before setting it up seems to be stuck in Decathlon's app forever.

I repeat:

Import a GPX File to Strava would require the PC and the Web-Version.

I want to use my Smartphone on my sport vacation only.

The synchronization does take time between two days and minutes...

---> How can I found out where the cause is (Decathlon Connect or Strava)?

How can I

​@Gubrist and ​@Drumbrakes -  please go ahead and disconnect from the application and then try reconnecting. You can disconnect from any third-party applications here:

https://www.strava.com/settings/apps
 

If that doesn’t help, we suggest reaching out to the Decathlon Connect directly for any questions. To provide some context, we have a publicly available API that hundreds of external developers use to integrate with Strava data. These integrations are built and maintained by those 3rd party developers which means that any troubleshooting questions are better directed their way.

Sorry about that and good luck!