The selected device could not be found
iPhone12Pro connected (with an Apple USB cable), to MacBook Pro running Catalina 10.15.7 and shows up in the left hand sidebar. I click it and the main screen says "Loading" with a spinning icon but after a few minutes I get the message "The selected device could not be found". Yet is is still showing up in the sidebar under "Locations". I've restarted the Mac, turned of the iPhone for a few minutes and reconnected it but still have the same issue. I once got the message to unlock the iPhone, and the "Do you Trust this Computer" messages and responded accordingly but still get the same message after a few minutes.
iPhone 12 Pro