Has a solution been found to this problem?  I've used Screenshot Captor for years but may have to ditch it.  I've got 3 x 4K monitors.  To the left and right are 2 wide screen curved monitors with size at 150%.  In the middle is a larger display (46") with 4K set but 100% text size.  More than 100% is too big for my large monitor and smaller than 150% is too small for the other monitors.  If I try to capture a region then everything changes as if it's just one screen spread across the middle and right monitors and so impossible to take a screenshot.  Changing to red box mode doesn't work because it won't capture due to security settings.

Thanks for all the effort that goes into this software.

Paul