The Print Screen key used to dim the display and let me select an area for a screenshot, but it suddenly stopped doing anything. This happened after the computer was unused for about two weeks and installed the latest Windows update. The setting to use Print Screen for screen capture is already enabled. Windows+Shift+S also does nothing, while Windows+Print Screen still captures the entire screen without offering the snipping selection.
3 Answers
Check Settings > Bluetooth & devices > Keyboard and make sure “Use the Print Screen key to open screen capture” is enabled. That option controls whether Print Screen launches the snipping overlay instead of taking a regular full-screen capture.
Windows+Print Screen is a separate shortcut that always saves a full-screen image, so it will not open the selection tool. Since both Print Screen and Windows+Shift+S are failing, the Snipping Tool or its shortcut registration may need to be repaired or reset in Windows settings.
Try restarting the computer first, then test the key with another keyboard if possible. You can also use Windows+Shift+S as an alternative shortcut, although that shortcut may need to be repaired if it is not responding either.

I checked that setting already, and it is enabled, so that does not seem to be the cause.