Scott E said
could this be part of the graphics issue introduced by Apple in Yosemite & continued (unresolved) in El Capitan?
people testing the new Mac OS ("Sierra"?) have suggested that it may be addressed in the new release this fall.
This graphics issue is not isolated to Toontrack or even solely to plugins.
Please Google it or check the Apple Support and forum.
Perhaps, I don't know 
First I've heard of it, I'll look into it