lumetri preset on an adjustment layer becomes invisible

[Michael Grenadier]

working in premiere 15.4 on a variety of machines, one windows, and 2 macs.  The first 2 minutes of a music video I'm cutting have an adjustment layer with the lumetri preset "monochrome normal contrast" applied.  no customization.  Usually when I launch the project, the adjustment layer is there with the lumetri preset applied, but it's not effecting the image.  If I delete the lumetri preset from the adjustment layer and reapply it, it's fine.    Not a serious issue, once I figured out how to fix it, just wondering if it's something in my workflow.  Source material is 3 cameras of 4k h264 all 24p which were used as multicamera sequences, but as we're almost done, I've flattened them, so I don't think that's an issue...