Unable to update Microsoft Remote Desktop

For the last several days, App Store says there is an update to MRD - but the display goes to "Pending" and leaves me with an endlessly circling throbber. I have rebooted, and restarted many times. Most recently, I used Launchpad to remove MRD, but the pending update still shows, and the symptoms remain the same. This is on a modern Intel 13 inch Macbook Pro, running Mojave. Thanks. (Although my older Macbook Air shows below this message - the newer machine did not show up among the list of my machines; and now I don't know how to change it)