If the systen uses RealTek go to Audio Manager, selelct 'Connector Settings' (the picture of a file) and unselect 'Disable front audio jack selection', i.e. there is no tick for this box.
I had the same problem on one of my new builds, and found this solution on Tom's Hardware.
Im using an aftermarket sound card. The Asus Xonar. And i cannot find that option in the software...