We tracked it down to the system telling us a display was both added and removed in a single callback. (Reported to Apple.) This new version mostly avoids this

We tracked it down to the system telling us a display was both added and removed in a single callback. (Reported to Apple.) This new version mostly avoids this bug, but there are still cases where it will appear briefly. We now fix it within a few minutes by polling the displays. Unfortunately, polling the online displays frequently uses more CPU & results in making MacBooks wake up much more slowly, so while we have a "bulletproof" fix we haven't been able to use it. Hopefully we'll be able to have a 100% solution soon but this build is a considerable improvement. We'll spend some more time testing and see if we can do better before it's out of beta.