SOLVED .....Hi there, I've had exactly the same drive spinning up and down issue and it's a new Monteray thing. I tried 2 different hard drives, a Lacie 12tb and now a WD Black series 12tb . After asking forums for help, the problem was solved by installing this App Store approved Amphetamine app and ie keeps your drive awake when you need it. PERFECT so far: https://apps.apple.com/us/app/amphetamine/id937984704?mt=12