To resolve the issue of workout videos not playing on your iPhone 15 Pro Max, follow these step-by-step troubleshooting methods:

1. Check Internet Connection: Ensure your iPhone is connected to a stable Wi-Fi network. A poor connection may hinder streaming videos.

2. Restart the App: Close the workout app completely and reopen it. This can help refresh the app's functionality.

3. Update the App: Go to the App Store and check for updates to the fitness app. An outdated version may contain bugs that have been fixed in newer releases.

4. Clear Cache: For apps that allow cache clearing, do this by going into the app settings. This can help eliminate any corrupted data that might be causing playback issues - learn more.

5. Re-download Content: If specific videos are unavailable, try removing the download and re-downloading them. This can often resolve playback issues - learn more.

6. Restart Your Device: Simply rebooting your iPhone can sometimes resolve underlying issues that may be affecting app performance.

7. Adjust App Permissions: Ensure that the app has the necessary permissions enabled, such as access to cellular data or location, if applicable.

8. Factory Reset (as a last resort): If none of the above methods work, consider resetting your device settings. Go to Settings > General > Reset > Reset All Settings. Keep in mind this will erase your device settings but not your data.

By going through these steps, you should be able to troubleshoot the playback issue effectively. If problems persist, consider reaching out to Apple Support for further assistance - learn more.