Problem: You can turn on but not turn off Location Services.
Root Cause: When you turn on Location Services, the iOS defaults the 'Share My Location' to on. However, if you have the supervised profile setting 'Allow modifying Find My Friends settings' disabled, the end-user cannot disable this and in-turn this prevents the end-user being able to turn off 'Location Services'.
You can confirm this by going in to General -> Privacy -> Location Services -> Systems Services:
Fix / Workaround: Enable the setting 'Allow modifying Find My Friends settings'
The specific profile setting that needs enabled is:
I hope this helps anyone else who might have stumbled across this. An interesting one for sure!