As my first post indicated, I am certain yes that it is plug-in related when it comes to LPX. This doesn't make it any less of High Sierra's fault. It also doesn't negate the GUI issues I spotted while using the OS for just a few minutes before quickly jumping ship and heading back to the shores of 10.12.6
Good luck! I am certain you will also start seeing issues creep up on you. I don't know how "professional" or deep you get, but I use LPX, Pro Tools, Ableton Live, and Reason all on a regular basis. I know there would have been a ton more issues with DAWs and plug-ins. I didn't stick around to find out. Seeing as I own every UA plug-in made and use their Apollo 8 interface along with 2 satellites, I don't have time to be fumbling around.
Cheers
[doublepost=1506022714][/doublepost]Just a side note... I feel Apple is sadly starting to lose its way. I say starting to, but this has been a long time coming. Especially in regards to fit and finish of their products and their UX and UE. They need to slow their roll and stop beta testing on the masses and get their act together.