Possible solutions are:
- Relaunching the Keyboard Maestro Engine (Quit Engine, Launch Engine).
- Restarting
- Toggling the accessibility permissions for Keyboard Maestro and Keyboard Maestro Engine off and then on again (probably while Keyboard Maestro and Keyboard Maestro Engine are not running)
- Run the Terminal command “tccutil reset Accessibility” (probably while Keyboard Maestro and Keyboard Maestro Engine are not running) and then launch Keyboard Maestro and allow the permissions.
- Quit Keyboard Maestro and Keyboard Maestro Engine, trash the Keyboard Maestro.app, empty the trash, download a fresh copy from https://files.stairways.com, use the Finder to move the Keyboard Maestro.app to the /Applications folder, and retry any of the above.
If none of that works then I am out of suggestions and until some other thing presents itself it may require a fix from Apple.