Yup, when I did a 20.04 install from scratch, same thing happened. Catkiller had me copy the contents of /usr/share/doc/wine-stable/examples/ from the 18.04 system that worked to /usr/share/applications in the new 20.04 system, and after a few reboots, i was back in business. Looking in /usr/share/applications in the 20.04 system, I now see the wineglass icon for "Wine Windows Program Loader," which I guess did the trick.

So what I'd do is see if that file is in either of the two locations on the 20.04 system that works, and copy it to /usr/share/applications in the deficient system.

BTW, I'm not much more than beginner level with Lubuntu, just a script kiddie who gets a lot of help from this forum, and this is the first time anyone has actually asked *me* for help!