I'm not totally clear on what you're talking about, but from what I can make of your post, I think we're having the same problem (?). Dual monitor setup (1440p, not 4k), OSX, Trashcan (D500). When I launch an Adobe app, the mouse position is registered improperly by the app, if I'm trying to drag an item into a bin, the item will often end up in the wrong bin, as the app thinks the mouse is around 75-80 pix lower than it's appearing on screen. Same thing happens when dragging footage around in the timeline --- the clip will end up on the wrong track. FWIW, this only happens on our Trashcan; the Windows computers and iMacs are fine. After beating my head against the wall, my best guess is that it's an OSX issue; I first started seeing it after updating to, I think, El Capitan (??? who can keep track of these stupid OS names any more...?); no issues with 10.9 (OSX Zip Zorpo or whatever it's called). The problem occurs with all versions of Premiere, AE and Audition installed on the machine, as well as one or two other apps -- basically anything that runs in a dual-monitor workspace spanning both screens (workspaces with undocked, floating panels don't exhibit the same problem). The problem occurs in versions of CC that had been installed (and working just fine) before the OSX update, so I don't see how it can possibly be an Adobe bug. I'm not exactly holding my breath for a fix from Apple; I've found that the simplest workaround is just to slightly re-size the program window -- grab the bottom right corner of the program window, drag it up a little, then back down to where it was. It takes about 2 seconds, and lasts until you close the program. When you re-open, you'll have to repeat the process. That seems to force OSX to re-adjust where it thinks elements of the UI are, and everything functions as normal again.
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