Unable to set a shortcut to grab screenshot area

Solution 1:

I made up a series of commands to show us the passive grabs on a keystroke. While the Take a screenshot of the area setting is set to Shift+Print please run this command and post its output.

xdotool keydown "shift+Print"; xdotool key "XF86LogGrabInfo"; xdotool keyup "Print"; sleep 1; xdotool keyup "shift"; tail /var/log/Xorg.0.log

This will trigger Shift+PrtSc keyevent and should show gnome-settings-daemon grabbing the keyboard.

Please also check if maybe some modifier key is activated on your keyboard and maybe somehow it is interfering with this keycombo. (e.g NumLock, ScrollLock, or some similar keyboard specific thing) Try out the combo with turning those modifiers on/off.