In Mail, I can't get main message to show up
This has happened before, but not often. I just reinstalled Mojave on a new SSD, and now when Mail comes up, there's no message below the list of entries. And there's no clear way of getting the message to show up. Trying to use the "expand" arrow should work, but doesn't. Earlier, I was told to Force Quit Mail a few times until it worked, but there isn't any Force Quit option in the Mail menu any more. Can anybody come up with a solution? In case this isn't a clear presentation, see the attached screenshot.
Mac Pro