Slider sits at the halfway height regardless of actual brightness

[glitchcrab]

I've seen an issue where after using the slider to adjust the brightness, the slider position returns to the middle even though the brightness has changed - the correct percentage is reflected in the text above the slider though and the lights are set correctly.

The only time this doesn't happen is if I pull the slider all the way to the bottom - the brightness then gets set to 'off' and the slider stays at the bottom. However, if the lights are already off before I open the popup, the slider will still be in the middle and the text will be '0%' (instead of 'off').