50" XJ90 Light sensor not working

[Logan1769]

I bought an XJ90 the other day and one problem I've got with my set is the light sensor doesn't seem to work. On my other tv, the xh950 the backlight dims instantly when I select light sensor, even if the brightness is set to 0 beforehand. 
On the J90 there's no difference in brightness whatsoever when I select it including toggling both options underneath. It does dim briefly while I select it to "on" but returns to the previous brightness when I confirm.

Has anybody else got this problem? Looking at some other forums it seems Sony accidentally disabled the light sensor in a previous update but are yet to add it back in.

[Logan1769]

I obviously meant X90J ,sorry for the typo. 

[HannahEd01]

Hey Logan1769, the light sensor isn't supposed to dim the screen unconditionally, it reads the room's light and adjusts to it. 

However, did you try any steps? Unplugging the TV from the mains? Removing external devices? Updating the software version? Or even a factory reset?