Icon not showing in Linux taskbar

[slavid]

What is happening?
The icon in the MATE taskbar (called "Window List") is missing when the Notion runs. It shows only in the window that it is oppened for a few seconds when launching Notion that says "Launching Notion".
I can see the icon when alt-tabbing though.
What should be happening?
The Notion icon should show.
Screenshots (if applicable):
Notion running shows an empty icon:

Image of Notion starting that shows the icon in the "Starting Notion" empty window (this video only exists for like 2 seconds before disappearing and then only the main Notion window exists):

Operating system/browser name & version:
Manjaro (Arch Linux) Kernel 6.5.5-1 x86_64 on MATE Desktop 1.26.1
notion-enhancer and/or notion-repackaged version:
notion-repackaged (from AUR repository) [vanilla port of notion to linux] link
notion-enhancer configuration (enabled/disabled mods and their settings):

---

Content of my notion-app.desktop file:

[Desktop Entry]
Name=Notion
Exec=/opt/Notion/notion-app %U
Terminal=false
Type=Application
Icon=notion-app
StartupWMClass=notion-app
StartupNotify=true
Comment=The all-in-one workspace for your notes and tasks
MimeType=x-scheme-handler/notion;x-scheme-handler/notion;x-scheme-handler/notion;x-scheme-handler/notion;x-scheme-handler/notion;x-scheme-handler/notion;x-scheme-handler/notion;
Categories=Office;Utility;

---

Icon locations:

$ find /usr/share/icons/ -iname notion-app*
/usr/share/icons/hicolor/48x48/apps/notion-app.png
/usr/share/icons/hicolor/64x64/apps/notion-app.png
/usr/share/icons/hicolor/32x32/apps/notion-app.png
/usr/share/icons/hicolor/24x24/apps/notion-app.png
/usr/share/icons/hicolor/512x512/apps/notion-app.png
/usr/share/icons/hicolor/256x256/apps/notion-app.png
/usr/share/icons/hicolor/22x22/apps/notion-app.png
/usr/share/icons/hicolor/16x16/apps/notion-app.png
/usr/share/icons/hicolor/128x128/apps/notion-app.png