Some apps have no icons or maybe invalid ones. Neovim, for example, has no ".desktop" file, and MPV has a .desktop file - but it seems like its icon is invalid, even though it is described in /usr/share/applications/mpv.desktop:
[Desktop Entry] Type=Application Name=mpv Media Player ... Icon=mpv ... Categories=AudioVideo;Audio;Video;Player;TV;
Since there's no icon, they cannot be clicked (even their names) and so they cannot be executed from the homescreen.
- Maybe there could be a fallback icon;
- Maybe their name could be clickable;
- Maybe click could be related to their region - or, like 1., have a fallback icon that is just an empty image that fills the icon rectangle.