Solo Audio Channel ATEM TVS HD?

Trying to monitor a single camera channel while the mix plays out through program. Is there a way to do this with the TV Studio HD? I’ve searched here and I’ve seen threads that say it can... but my solo headphones icons in the control software are all greyed out. The documentation is vague. Suggestions?

This is so I can monitor a Skype caller that is coming in through an SDI port, but I don’t want to hear my own audio, which has a slight delay.

Not sure if the TVS supports this...but start by checking in audio settings (gear icon) that the Audio Monitor outputs are: --- set to Monitor audio, not program audio. On the bigger ATEMs, when you change this to Monitor audio it enables the solo/headphone buttons on each input channel. Monitor audio is the same as program, until you click one of the headphone buttons to preview a single input source. Clicking it off returns the monitors to the program mix.