GPO not applying mapped drives

I've been trying unsuccessfully to apply 2 mapped drives to all users using GPO. I've successfully applied desktop shortcuts to the server.

I've checked the logs on the client computers and they state that 3 policies have successfully been applied.

These are the settings I've tried:

User Configuration > Preferences > Drive Maps

- Create
- \\PHIL\files
- label: Files

- Drive letter Use: F

- Common: Run in logged in users security.

Any advise on how to debug this?

Thanks