This always makes it clear what you've got in your scene for sources. In my experience, don't use the Audio pane in OBS add explicit sources to scenes. You will also need to add your microphone separately, as Skype will only be sending its output to this device. Set Skype to use your LoopBack Audio virtual device as its output, and then add that device as a source in your OBS scene. I haven't tried using Loopback with Google Voice and I don't use Skype anymore, but I bet it would work with Skype. Why bother adding as a source if you're going to mute it?
