Why does an app show as Blocked with "Currently running"?

Short answer: The app is open, and open apps can't be moved safely. Quit it fully (including any menu bar part), refresh the list, and the Move button returns.

Because it's open, and an open app can't be moved safely. Quit the app, refresh the Apps list, and it gets its normal badge and Move button back.

If it still shows as running, check for a menu bar icon or a background part of the app that's still open, and quit that too.