When changing notifications, changing one notification with the "Play a sound" option enabled by clicking the "Open file dialogue" button opens the file dialogue and allows you to navigate as expected. On my system, the dialogue was configured to show the sidebar and automatically play audio files by default.

After selecting the file I wanted and clicking "OK" or clicking on the desired file correctly sets the file to be the notification sound.

Then, when selecting a different notification with the "Play a sound" option enabled, and when clicking the "Open file dialogue" button to change the sound, a loading wheel appears for a brief period before ending without opening the file dialogue. The dialogue never opens no matter how long I wait.

Resizing the KCM window causes it to repaint correctly, but otherwise, clicking on UI widgets such as buttons or text areas does nothing, nor does using the standard window manager method of closing the window. I was forced to kill the application in order to make it close.

Reproducible: Always