When spanning a wallpaper across my two monitors, I see this black bar atop my main monitor (#2 in the picture). It doesn't show in Display Fusion as black, and I can confirm there's more to the image (adding a negative vertical offset reveals more of the image, rather than widening the black bar)... The area is also active (the RMB context menu of this monitor confirms it's 3440x1440).
Maybe it's the same issue in the URL above that's yet to be addressed?
