Display turning off when device is locked

Hello,

I have a requirement where I need a devices screen to stay on when the device is locked. 

The device will turn the display off after around 10 seconds.

Our power settings are enforced properly when the user is logged in but the device isn't locked.

I am wondering if anyone has pointers toward any specific setting which could affect this behaviour?

I have played with setting unattended sleep timeout to 0 and this doesn't help. This has also been set to 10 hours to see if it would help at all, this does not either.

Thank you,

Jamie.