Steven, Thank you for the really fast reply.
A truly amazing – for me – thing happened and I am utterly unable to understand why!
I deactivated all plugins except Connections as per your reply BUT when I logged back to the plugin area, all were reactivated and the problem went away – I think that I must have clicked on the wrong bulk action item. I noticed that the ManageWPWorker plugin – it is used by Manage WP – was no longer there so I reinstalled it. The problem returned. So there you have it – the ManageWPWorker plugin was the cause of the problem. BUT, I had several other problems with the site which is running the Professional “Child” Theme which I was working on and they ALL resolved themselves! That’s the part I just don’t understand.
In your experience, does simply deactivating all plugins and then reactivating them somehow acts like a reset?
Anyway, thanks for the help. I really appreciate it.