When I plug my phone into my dock that is in turn plugged into HDMI1 on my monitor the sound works with no problems (HDMI2 is my normal PC) but then my monitor has built in speakers.
If you use speakers plugged into your PC or sound card, I wouldn't expect them to work as you are not going the right route. In other words the sound is going HDMI to your monitor so unless your speakers are also using that HDMI connection (Plugged into your monitor) they will not work.
If I use the Wireless connection in the back of my TV I also get no sound as the output to the amp I have plugged in gets it's source from my Xbox One on HDMI 1 and not the wireless connection on HDM1 2, I would need to make a change to the sound output wiring (So plug a different source into amp to make it work).
None of this may apply to you, but worth thinking through.
EDIT, Sound does work through my TV, just had the volume turned down to 0 as we normally listen through the receiver mentioned.