I can confirm the stated behaviour on my machine as well. I believe dcarpenter was referring to the "Toggle audio recording from capture" button [ the 50s style microphone in his screengrab ]. When you click the microphone the X is removed but upon closing and reloading gnome-volume-control the X reappears, suggesting that the input cannot be used for recording. However, it works.
I can confirm the stated behaviour on my machine as well. I believe dcarpenter was referring to the "Toggle audio recording from capture" button [ the 50s style microphone in his screengrab ]. When you click the microphone the X is removed but upon closing and reloading gnome-volume- control the X reappears, suggesting that the input cannot be used for recording. However, it works.