This just started showing up on my Cintiq 21UX and iMac - Hoping it doesn't get worse, but wanting to document it in case anybody else finds a solution or solace in knowing they are not alone.

I considered the Thunderbolt > DVI cable, but have made sure it is snug. Nothing has changed in the past 2 years of operation, and the tablet was purchased new.

Will update if anything is resolved or it gets worse.