I've seen this in the past, but don't remember the fix. There's bleed through at the top of this Multicam. Resizing will temporarily fix this, but it comes back. The system is a windows 10, 24 Core Z8 G4 with 64GB of RAM, a 10Gb Ethernet connection and a Quadro P4000. It's running MC 2018.12. Is it an overlay issue?
That's my thinking. They're running MC 2018.12.8 with Nvidia driver 411.95, which I believe Avid had them update to for another issue. Looking at the compatibility documentation it does say "If you have a Quadro 4000 graphics card remain on the Nvidia v353.82 driver". They have a Quadro P4000 so that might be the answer.