"Add to favorites" is listed for hidden .desktop files, but doesn't work

Initially reported to Pop!_OS.

Affected version

• Pop!_OS 20.10 with Gnome Shell 3.38.1
• Reproduced on Fedora Rawhide with Gnome Shell 3.38.1

Steps to reproduce

1. Install the Caja package (for instance) from apt or dnf
2. Start caja from terminal
3. Right click on icon, and click "add to favorites"
4. Close Caja. It is no longer in the dock.

Removing the lines NoDisplay=true and OnlyShowIn=MATE; from /usr/share/applications/caja.desktop makes adding to the dock work.

What did you expect to happen

Either "Add to Favorites" shouldn't be shown for hidden .desktop files (like programs with no .desktop). Or it should work.