I have lost control of Lightroom Classic on my new imac (S 15.2. I can't move images into a new folder. I get an error message that says that file(whcih contains other files) cannot be written to. My catalogue is on an external drive. It also soes not repond to mouse clicks.
That may be a security permissions issue. Go to Sysyem Preferences>Security & Privacy>Privacy tab>Files & Folders and make sure Lightroom Classic has access to the various items (Removable Volumes, Network Volumes, etc.).