Screenshot Problem using Capture Selected Area

This has been going on for a while but it's still happening. If I want to record a part of a window/screen for reporting an error or to include in a document; I can select the area, press capture, the capture takes place but the area where the capture was taken is normal but everything else is grey. No issues with using the screen but just irritating and it needs a reboot to correct.

Is there another way to fix as a restart needs me to save everything I am doing, which could take a few minutes