Hello,
I have an uDMX Device that worked great with Mac OS Sierra but since i updated to Mac OS High Sierra it just works for a few seconds.
I already tried all suggested solutions I got from Google and from this Forum even reinstalling QLC+.
When I plug it into my USB Port and then start QLC+ the Status LED turns from red to green and I can control my Lightings.
After a few seconds the LED turns red again and I'm not able to control anything.
If I disable the uDMX output then rescan for devices and then turn on the uDMX output again it works again for a few seconds.
As said it worked fine until I updated my OS.
Alex
Q Light Controller+
Official forums of the QLC+ project