bevy: KeyCode::Plus (Minus) not working correctly

Bevy version 0.5 Windows 10

What you did

Used following system to zoom in and out. KeyCode::PageDown and PageUp are working. KeyCode::Minus is only working with the normal Minus key, not the one from the NumPad. Also KeyCode::Plus does not work with Plus key or NumPad Plus key. I use a german Keyboard layout.

fn zoom(keyboard_input: Res<Input<KeyCode>>, mut query: Query<(&mut Transform), With<Camera>>) {
    let mut dir = 0.0;
    if keyboard_input.pressed(KeyCode::PageDown) || keyboard_input.pressed(KeyCode::Plus) {
        dir = -0.7;
    }

    if keyboard_input.pressed(KeyCode::PageUp) || keyboard_input.pressed(KeyCode::Minus) {
        dir = 0.7;
    }

    if dir != 0.0 {
        if let Ok(mut transform) = query.single_mut() {
            transform.scale.x += dir * TIME_STEP;
            transform.scale.y += dir * TIME_STEP;
            transform.scale.x = transform.scale.x.clamp(0.5, 2.0);
            transform.scale.y = transform.scale.y.clamp(0.5, 2.0);
        }
    }

    if keyboard_input.pressed(KeyCode::End) {
        if let Ok(mut transform) = query.single_mut() {
            transform.scale.x = 1.0;
            transform.scale.y = 1.0;
        }
    }
}

What you expected to happen

Korrect key recognition.

What actually happened

No or not all key recognitions.

Additional information

Used german Keyboard layout.

Any additional information you would like to add such as screenshots, logs, etc.