The default hot key for Snapz Pro X changed to Command-Shift-5 (⌘⇧5) with the release of version 2.5. The hot key may fail to work properly if there is a conflict with another application or OS based keyboard shortcut. You can either change Snapz's hot key or resolve the conflict. To change Snapz's hot key:
Since Snapz is unable to detect conflicts automatically, you will need to check your System Preferences > Keyboard > Keyboard Shortcuts windows as well as any running applications to clear any conflicts.