I have the same issue. The Fitness app will also not show the routes of runs I did before I did the iOS15/WatchOS7 upgrade. Now, I get no GPS route, just a map with a start point marked.
I have cleared and restored the watch from a backup, I have the 'location tracking' set to 'allow when App in use'. Still, it does not include the path.
I have done a run with Strava on the watch, and it correctly uploaded the GPS route to Strava, so the hardware is ok, and the permissions are ok. Workout just seems to not upload the data.
I use another app, HealthFit to upload Workout data to strava or icloud, it is extracting the data from iOS Health. It now exports without GPS route data. It is also now unable to export old (pre iOS14) workouts. So it seems to me that Workout is not saving the data, and the renamed Fitness app can't read the old format of data, and the API has somehow changed since HealthFit cannot now access the old (pre iOS14) GPS routes.
hmm.... back to using the Garmin watch (or the Strava App)