I want to add another post to this thread, but since I posted last, it appears that my new "answer" is being appended to the one I last wrote, which was from about four hours ago.
Anyway, the TV suddenly started working right. I don't know why. I turned it on and got an alert that the system had been updated (I had previously enabled auto-update). Now apps are also installing. So, all is now as I expected it to be.