If you lose Live Commentary audio when streaming or recording, when using Elgato Game Capture HD software for macOS, the following steps may resolve that problem.

1) Change the Audio input in the Device section of the Elgato Game Capture HD software to the other choice.  For example, if it was on Analog, change it to HDMI.  If it was on HDMI, change to Analog.

2) Close the Elgato Game Capture HD software.

3) Reopen the Elgato Game Capture HD software.

4) Change the Audio input back to what it was - your preferred choice.

5) Try recording your Live Commentary again.

Note from Andrea: Internal mic audio stopped in EGCM 2.11.5. A combo of updating to latest EGCM, erasing prefs/caches and new user account fixed the issue