Have you just installed the software?
If so do the following. Restart the Mac. As soon as it boots up to the desktop (Finder) again, go to the Apple Menu, then System Preferences, Security & Privacy. At the bottom you should see a button that says 'Allow'. Click that. Then load up Logic and all should be well.
Thanx so muuuuuch , bro! Savin' lives over the years!