COD: Mobile auto login not happening in Gameloop is one of those problems that's been around for years.
Reinstall
1. Uninstall the Gameloop with a uninstaller software like Revo Uninstaller.
- Revo has a 30 days free trail. [https://www.revouninstaller.com/]
2. Look for Gameloop's install folder and delete it.
3. Reinstall the Gameloop from the official site. [https://www.gameloop.com/]