Hi.
You have the same 2 x 4K screen setup that I use.
Are you using a separate instance of SketchUp on each screen or just separating the trays onto the 2nd screen?
I recently gave up trying to run 2 instances on separate screens as it resulted in instant crashes.
I used to copy and paste between instances but now I have to rely on the import function which requires a bit more work.
Kevin