Removed: libreoffice-calc.desktop
Ran: kbuildsycoca4 --nonincremental

No apparent change. Of course the desktop icons are running with soffice in their commands, now, anyway.

After a couple of restarts, there remains NO libreoffice-calc.desktop file in the .local/share/applications folder.

Ok, this means Libreoffice Calc should be in your menu again.

Unfortunately there isn't much you can do other than tweak the shortcuts until the developers fix the Folder view code for now.

Thanks, bcooksley.

It is always a pleasure to work with others on issues in KDE. The helpful community spirit overrides the tension of trying to deal with a problem, whether it is a bug or not. Thanks to everyone who added to this conversation, too.

My "problem" is solved. I can again use the icons for the two files I must open daily, and do so with a single click.

I had the similar problem and faced it a lot of times. I often solve this type of problems using "Long Path Tool". Try it and it may surely help you.