This issue affects the LS30 and LS40 headsets only.
Apple released an update to their MacOS recently called High Sierra. With this update, users are reporting that the "LucidSound PC Chat Audio" device no longer appears in the Sound Output or Input. As a result, no mic input is available for the headset.
We're working to find a solution. In the meantime we have discovered this workaround:
If you connect the optical cable to the USB dongle and then plug the dongle into the USB port you will cause the dongle to switch modes. You don't have to connect the other end to anything.
You should now see an output device called "LucidSound" and an input device called "LucidSound." This allows the mic to work and you'll be able to hear audio playback.
Here are the limitations to this setup:
1. All the audio is controlled by the right volume wheel.
2. None of the EQ modes will have any effect on the sound coming through since it's all running through the "chat" channel. You can however use the EQ on your Mac (i.e. the one in iTunes) to control EQ if desired.
3. The left volume wheel will only control the level of your mic monitor (how loudly you hear yourself in the headset).
If your Mac has an optical output port you can use that to route audio to the headset and resume normal operation. Some Macs use a combo headset/optical port and require a Mini-toslink adapter as linked.
Set your Mac to use the digital optical output for audio and then use the USB audio "LucidSound" for your chat programs and get the same functionality as you had before the High Sierra update. This would then allow you to control music/game/move audio separately from the chat application volume and the EQ modes will work (including surround sound from Dolby Digital content such as a DVD if you have an LS40).