When using the auto-hide panel at the bottom of the screen, and the panel is showing. I can get OSD notifations for volume up/down and brightness up/down fine at first. However, once the panel hides, using the volume up/down shortcuts no longer shows the OSD. It does still change the volume though. But if I mouse over the bottom of the screen as to bring up the panel, and then use the shortcut again, the OSD will again function properly... until the panel hides and all existing OSDs are removed.

Is this behavior intended? I've currently changed to the Windows Can Cover option instead to retain the OSD functionality.

Edit: My plasma version is 5.8.3

This is a bug which we recently investigated and fixed. Will be fixed with the next frameworks release.

For more info about it, see https://bugs.kde.org/show_bug.cgi?id=370433