Missing icon on panel by custom launcher

[TommasoDb]

Describe the bug
I manually added a desktop launcher to my system by adding a .desktop file in the directory /usr/share/applications.
If I run the application, the icon does not appear in the panel

I copied the icon the directory /usr/share/pixmaps/ and I added the absolute path to the .desktop file.

In other Gnome-Shell menu, app and icon look fine. See screenshot

Linux distribution and version
Ubuntu 24.04

GNOME Shell version
GNOME Shell 46.0

Dash-to-Panel version
62

Where was Dash-to-Panel installed from?
The GNOME extensions website

Screenshots / Video captures
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Additional Info