Cannot Get appimage to work for 3.6 and 4.1

Hello Musescore People:

I use linux (Ubuntu 20.04) and downloaded Musescore 4 from https://musescore.org/en/download and also Musescore 3.6 from https://github.com/musescore/MuseScore/releases?q=3.6.2

I moved both appimages to my desktop, checked that I owned it, and gave both executable (right click > properties > permissions > Allow executing as a file program

Then, I right clicked on the appimage and selected run as a program.

Then... nothing happened.

I followed this procedure for both 4 and 3.6

How can I make one or both of these appimages work, please?

Greatfully,
Trying Harder