In my case it pauses at "Copying shared cache symbols from Apple Watch (13% completed) Xcode will continue when the operation completes." and then "Apple Watch may need to be unlocked to recover from previously reported preparation errors Ensure the device is unlocked and near this Mac for better connection quality." I removed passcode from the watch, put in on my wrist and kept tapping the screen to keep it always on, to no avail. What a joke Apple has become!