UPDATE: Sorry. This is resolved after updating to the latest Windows 10 update (November 2019). I also observed this same deadspot in another game, Frostpunk, when moving my cursor over the same region so I believed it was a windows 10 issue.
Recently, I’ve been experiencing something similar to this post:
where there is an unclickable part of the screen above the command card region (middle right side of screen). If I mouse over this small region, the cursor changes from the sc2 in-game cursor, to the default windows cursor. Moreover, I cannot click on anything within that region (units, buildings etc.). I have always been running in windowed border-less mode.
I’ve restarted the game multiple times, and rebooted computer. I also did a “scan and repair files” from the blizzard launcher. I also tried the old post solution of changing resolution back and forth but have seen no success.