Mac running Monterey suddenly turned my Logic Pro X app icon to gray.

Running Monterey 12.7.6 on Mac Pro. Having been running Logic Pro X with no problem for several years. Recently copied Logic app from Applications folder to and external drive to free up space on my main drive. The app icon turned gray and won't open. The error says my version of Logic won't run on my Monterey OS. Problem is it was running fine on Monterey until I copied the app to an external drive. Apple says they can't help me get it back. Any suggestions?