For a while the WD worked automatically ( I didn’t have to do anything) when I bought my Mac few years ago. Then it stopped working, and Time Machine says the drive is unavailable. Downloaded WD App Manager, which does absolutely nothing. Nothing happens when I open it. WD Utility brings up an empty screen asking me to connect the drives, but there is nothing to connect.
Have you tried resetting the unit and checking the physical connections?
Yes. Several times. Does not help. Even if there was a loose connection, it would not explain why the software does not bring up the WD App Manager.