Hi !

I use Debian (buster) and the latest kdenlive-19.03.70-68574e5-x86_64.appimage.

When I press F1 in Kdenlive 19.03.70 I get this in the console :

qt.qpa.plugin: Could not find the Qt platform plugin "xcb" in ""
This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.

I did a search on internet, and I have the required libqxcb.so library that seems to correspond to qt.qpa.plugin.
I installed additional libraries : libxcb1-dev libxcb-util0 libxcb-util0
I restarted KDE.
I still have the problem.

Thank you for your attention !