Here's a video (OBS display capture) that shows a few captures and most importantly, SHIFT + PRTSCN for a selected region.
You can see how SSC "can't see" the right side of bottom of the screen.
And here are some screenshots with info about the 8k monitor setup:
Screen 3 is the primary display.
[ BUG REPORT ] - Maximum screenshot resolution too lowNotice that "Scale and layout" is set to 150%. This is to improve font clarity and size. It doesn't work perfectly. (See "VLC media player" and the "Windows Explorer" shots below.)
[ BUG REPORT ] - Maximum screenshot resolution too low[ BUG REPORT ] - Maximum screenshot resolution too low[ BUG REPORT ] - Maximum screenshot resolution too lowNotice the various font sizes and overflow problems. Windows scaling isn't perfect.
[ BUG REPORT ] - Maximum screenshot resolution too lowNotice the small text in the status bar at the bottom.