I've tried the latest and an older version from Dell's site, the latest from Intel's site and the Microsoft default and all exhibit the same problem. It's the only application having the issue to date, but was rock solid on Windows 10.
As I'm writing this though, Dell has just released a new GPU driver - So I'll give that a crack and report back
Another possibility is tools that modify windows to make them translucent or on-top, but I'd expect them to normally affect the border/titlebar as well.
Disabling transition animations (Preferences / Display / Transition Animations) is worth a try, as it's the mostly likely thing to trigger bugs in GPU drivers. If you click the window icon at the top-left of the lister, there should be an item in the menu that appears there to open Preferences, although it's possible the Preferences window itself will then have the same problem.
I've been playing around with it a little this morning, and noticed the following:
New GPU Drivers haven't made any difference
Disabling Transition Animations in DOpus Preferences didn't resolve the issue
It occurs far more often when undocked and running from just the laptop display
Appears to only trigger when clicking a PDF Document > Caused by the Preview Pane
When the Preview Pane is closed, the issue no longer appears to trigger
I've changed the Preview Handler to Adobe Acrobat, and it appears to be stable at the moment. It hasn't been long since the change though, so time will tell if this workaround resolves the isuse.
It appears that the Windows Explorer Preview Pane will use Microsoft's Default PDF Previewer regardless of what is set as the default PDF application (Based off the right-click options and iconography), and it does work completely fine.
I suppose if the issue only affects me, then setting Adobe Acrobat as the preview app in DOpus has resolved the problem and I haven't seen it happen again since