Strava activities via Apple Health
We can only import activities that have the route data sent to Apple Health, which not all apps do.
You can confirm if your activity has no route:
Open your latest activity via Apple Activity app
Go to Workouts and scroll to the bottom
You should see a map with the route plotted on it for Relive to be able to create a video.
If there is no map with the route, then it seems that your tracker doesn’t share the route data into Apple Health, which means we can’t pick it up.
If you track your activities with an Apple Watch, you can consider making use of the built-in Apple Watch tracker to record your activities. This way, your data will be sent and can be used by another tracker app and Relive.