Decklink Extreme not an audio output option in macOS 10.13

I'm running Blackmagic Video Desktop 10.9.7, and my Decklink Extreme 4k seems to work fine with Media Composer 8.8.2 (MC isn't yet certified for macOS High Sierra, but I'm just trying it out on a separate boot partition). I noticed video and audio seemed out of sync in Media Composer, and I wanted to double-check by exporting the video and playing it with quicktime player. Normally on Sierra I've got my System audio going out the Decklink Extreme. But in High Sierra I don't see it as an available option:

2017-10-18 at 9.51 PM.jpg (35.12 KiB) Viewed 606 times

It's also missing from Audio Midi Setup.

Looks like the problem resolved itself after a reboot. I again have Blackmagic Decklink 4K Extreme as a system Sound Output option.

But video and audio from Media Composer still play out of sync out the SDI of the DeckLink Extreme in macOS 10.13 with BlackMagic Video Desktop 10.9.7 --but they're in sync from Davinci Resolve on the same machine. I suppose this might be the sort of problem that Avid will fix by the time they certify Media Composer for High Sierra.

And now with Blackmagic Video Desktop 10.9.10, I had system audio working and was cutting in Media Composer while playing music in iTunes. I received a phone call, the computer started ringing loudly due to handoff. I answered on the phone, ringing stopped, and the Blackmagic Decklink Extreme disappeared as a system audio device - iTunes nor the System at large could play audio through it. Media Composer is able to continue using the device for output, but not the System.

I don't really feel like rebooting in order to get music to continue playing back, I've got work to do. I hope this bug doesn't last forever.