gsd-backlight-helper works but gnome slider / fn keys doesn't

I have a Dell XPS 9700, and I'm having a strange issue with the backlight in gnome.

The kernel seems to correctly initialize/detect the device and /sys/class/backlight/intel_backlight exists. Manually writing to the files or using gsd-backlight-helper correctly adjusts the brightness of the screen.

In gnome, though, both the brightness slider and using the fn keys does not seem to have any effect. When using the fn keys, gnome recognizes it and shows the popup/overlay with the slider moving but the brightness stays the same.

Let me know it there is any other information that would be helpful.