To address the issue of Rally not detecting your gym, Planet Fitness, follow these steps:

1. Check Location Settings: Ensure that the location services on your device are enabled. Go to your iPhone's Settings > Privacy & Security > Location Services and make sure they are turned on. Confirm that Rally has permission to access your location.

2. Update the Rally App: Check if there are any updates available for the Rally app. Open the App Store, search for Rally, and if there’s an update, tap on Update.

3. Restart the App: Close the Rally app completely and then reopen it. This can refresh the app and possibly resolve detection issues.

4. Search for Planet Fitness Manually: In the Rally app, try to manually search for Planet Fitness. Look for a search bar or a method to enter gym information directly.

5. Contact Rally Support: If Planet Fitness still isn't detected, consider reaching out to Rally’s customer support. They can assist you with specific issues and may be aware of any ongoing problems with gym detection.

6. Verify Gym Participation: Ensure that Planet Fitness is a participating partner in the Rally program. Sometimes, not all locations are included or may have recently changed their partnership status.

7. Reinstallation: As a last resort, uninstall and then reinstall the Rally app. This can clear out any corrupted data and ensure you have the latest version.

Following these steps should help you troubleshoot why Rally isn't detecting your Planet Fitness gym. If the issue persists, consider seeking further assistance from Rally's support team.