I've connected to a monitor (34UC88-B) to my MacBook Pro (Late 2016, no Touch Bar) through a DisplayPort to USB-C connector. The monitor has speakers that I use when I'm connected to it.

Everything works fine when it's working. No problems with the display or the sound.

However, when I disconnect the monitor from the MacBook OR when I leave it connected overnight and log in to my computer in the morning, the monitor speakers disappear from Sound Preferences and the sound comes from only my macbook's internal speakers.

I've tried disconnecting the monitor and reconnecting and switching off the monitor off and on. Nothing works.

The only thing that does work is restarting my MacBook. As soon as it restarts, I can see the monitor's speakers in the sound preferences again and I can switch to them without problem.

It's really annoying to restart my computer each time disconnect or get up in the morning. Logging off and on doesn’t work. Only a restart does. How do I fix this?

Before Restart (Monitor is connected and the display works) : enter image description here

After Restart: enter image description here

I don't know what the Apowersoft_AudioDevice is. When I switch to it, I get no sound.

  • A couple of things.... it's a Thunderbolt Type C port (according to LG). The first thing I would check is that you're using a TB Type C cable. Also, did you try contacting LG tech support? This sounds like an issue with the monitor. – Allan Jun 20 '18 at 11:35
  • It's a displayport. I've connected my macbook(usb-c) to the monitor(DisplayPort) using a usb-c to DisplayPort connector. I don't know how this can be an issue with the monitor as it does work perfectly fine when it's connected. It's only when disconnected or left idle the problem occurs. The speakers aren't recognized anymore. Is there any comment to manually trigger the recognition of all the speakers available? – Hemanth Jun 20 '18 at 12:30
  • @Hemanth did you ever find a solution to this? I have the exact same issue with my LG 4k monitor over usb-c, on a fresh boot my Mac recognises the speakers, on a wake it can't see them at all. – matthewrk Dec 13 '18 at 13:50

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