The version of Lumetri plug in has to be 11.1.0 which is the one that loads in the latest Premier build download.
On any clip in Basic Correction tools, lowering the blacks anywhere below 20-30 units causes the clip to go completely blocky and looks like low bit color space. Kind of hard to describe. It also oversaturates the black area and in some cases even changes the hue!
When we replaced only the Lumetri plug in back to 11.0.2 it worked perfectly. Nice smooth gradual change of blacks.
Had the same issue on 5 like legacy Mac Tower systems all running Yosemite and all having AJA Kona cards. We have a mix of ATI and Nvidia graphics cards but those did not make a difference between systems….it was always traced to the 11.1.0 version of Lumetri.
Rich Rubasch
Tilt Media Inc.
Video Production, Post, Studio Sound Stage
Founder/President/Editor/Designer/Animator
https://www.tiltmedia.com