DJay Pro + DDJ Ergo controller: headphones not working

I’m running DJay Pro (1.0.26524) on a Windows 10 computer. Using the Pioneer DDJ Ergo - V controller. All seems to work but I cannot configure the headphones to work. I have no sound when I press the ‘Cue’ Headphones buttons. I know I can map manually, but how would I have to configure them? (control name + target + action…)