Flatpack installation Qgis, Menue not working correctly

[APM]

Dear all,


I like to install qgis stable via flatpack on a Debian testing installation.

Further I use xfce4 desktop enviroment and an Intel grafik chip.


I installed Qgis stable with 'flatpak install --from 
https://flathub.org/repo/appstream/org.qgis.qgis.flatpakref'


Qgis is installed now and starts as expected by typing 'flatpak run 
org.qgis.qgis'.


One error message is shown at start:

Warning: Qt: Session management error: Authentication Rejected, reason : 
None of the authentication protocols specified are supported and 
host-based authentication failed

But If I try to open a project in Qgis by pressing the related menu 
button the menu not appears.

Same with other tasks like save etc.


flatpak run --command=sh --devel org.qgis.qgis
error: runtime/org.kde.Sdk/x86_64/5.15 not installed


flatpak list
Name                            Application 
ID                                            Version Zweig       
Installation
default org.freedesktop.Platform.GL.default 20.08       system
Intel org.freedesktop.Platform.VAAPI.Intel 18.08       system
Intel org.freedesktop.Platform.VAAPI.Intel 20.08       system
html5-codecs org.freedesktop.Platform.html5-codecs 18.08       system
openh264 org.freedesktop.Platform.openh264 2.1.0        2.0         system
Adwaita theme org.kde.KStyle.Adwaita 5.12        system
Adwaita theme org.kde.KStyle.Adwaita 5.15        system
KDE Application Platform org.kde.Platform 5.12        system
KDE Application Platform org.kde.Platform 5.15        system
QGnomePlatform org.kde.PlatformTheme.QGnomePlatform 5.12        system
QGnomePlatform org.kde.PlatformTheme.QGnomePlatform 5.15        system
QtSNI org.kde.PlatformTheme.QtSNI 5.12        system
QtSNI org.kde.PlatformTheme.QtSNI 5.15        system
QGnomePlatform-decoration 
org.kde.WaylandDecoration.QGnomePlatform-decoration 5.12        system
QGnomePlatform-decoration 
org.kde.WaylandDecoration.QGnomePlatform-decoration 5.15        system
QGIS-Desktop org.qgis.qgis 3.18.0       stable      system


Thank you for your help!


KR


Piet