Why there is no .desktop files generated when AppImage file is executed on Ubuntu?

Hi,
When I used the official recommended one-line script on my Ubuntu, it popped up Connection refused on the screen may be due to the bad network connection. Thus, I had to download the AppImage file and changed the permissions to run Joplin. I previously use the 1.0.176 version. And when the AppImage file is executed, it automatically generated the appimagekit-joplin.desktop file. Then I can launch Joplin from the Dash of Ubuntu. But yesterday when I executed the AppImage file with version 1.0.197 on another Ubuntu machine, it did not automatically generate the .desktop file. I think the way it automatically generates the .desktop file is favored. I am a little confused about why the newer version does not create the file? Another question is what else should I do to make Joplin works in the best condition if I launch Joplin with the AppImage file? It seems little is mentioned in the official instructions.
Any help would be much appreciated!