Wrong action executed for German localisation

I have a very strange problem with my app. As soon as I switch to German, the command to open Preferences (Cmd+,) in Apple menu invokes completely different command.

After a lot of debugging I discovered the following. This is the translation for one of the commands in the main menu:

<message>
 <location filename="../src/gui/mainwindow.ui" line="1657"/>
 <source>Save configuration</source>
 <translation>Konfiguration speichern</translation>
</message>

As soon as the word "Konfiguration" in translation is changed to something else ("Konfiguratiom" or "Konfiguration" but with ‍ inserted in the middle of the word), Preferences start working again.

I don't have a working minimal example and it need some time to prepare, so first I'd like to ask if it does even make sense? Is Qt doing something with the word "Konfiguration"?