DESCRIPTION
If you add an Application Menu button to the titlebar using System Settings, it doesn't display for some apps when run in Wayland. The same apps will show the Application Menu button in X11.

STEPS TO REPRODUCE
1. Login to a Plasma Wayland session
2. Run System Settings
3. Navigate to Colors & Themes > Window Decorations > three-dot menu > Configure Titlebar Buttons
4. Drag the Application Menu button to the Titlebar (I dragged it to the top-left, to the right of the Window Menu button, but I don't know if that matters)
5. Click Apply
6. Run any of the following apps:
   - Firefox (when configured to show a titlebar)
   - Thunderbird
   - Signal Desktop
   - VSCodium (when configured to show native titlebar)

OBSERVED RESULT
No Application Menu button in the titlebar.

EXPECTED RESULT
An Application Menu button in the titlebar.

SOFTWARE/OS VERSIONS
Operating System: openSUSE Tumbleweed 20260625
KDE Plasma Version: 6.7.1
KDE Frameworks Version: 6.27.0
Qt Version: 6.11.1
Kernel Version: 7.1.0-14063-g4edcdefd4083-1.g0e7f353-vanilla (64-bit)
Graphics Platform: Wayland

ADDITIONAL INFORMATION
The same apps do show an Application Menu button in the titlebar if run in an X11 Plasma session. Other apps I've tried (especially KDE apps) do show an Application Menu in the titlebar in both X11 and Wayland.