Hi @xavicx
Thanks for your post! One explanation for this issue is that GPS data isn't being recorded. You don't mention what you are using to record your activities; whether it is the Strava Mobile App or some other device. If it's the Strava Mobile App, check out the troubleshooting steps for Android or IOS phones, whichever is applicable.
If you're recording with a third party device or platform (for example Garmin or Wahoo), check your device and make sure GPS hasn't accidentally been disabled. We see this happen on Garmin devices fairly frequently. Another troubleshooting tip is to check the activity on the third party site (for example Garmin Connect site) and see if a map appears there. If it doesn't you'll know that the GPS wasn't recorded and synced to Strava.
If none of that helps, please submit a support ticket and we’ll be happy to investigate further.