04/10/2018: We contacted LG regarding the strange results in week 4. LG engineers visited our lab a few days ago and were able to confirm the 25% window on the Live CNN and FIFA 18 TVs are a result of a factory issue (
see our video here). OLED TVs are produced in a hot process, and after cooling a 25% window is shown on each panel. Some TVs which haven't cooled completely can produce invalid results for the lookup table used by the 'Pixel Refresh' function, causing this 25% window to become visible. Only some 55" OLED TVs were affected during part of 2017.
As this is not an issue with the panel itself, it is possible to apply a fix to the lookup table. LG will apply this fix to anyone who presents this issue to their support, for free, even after the warranty period has long expired. They have fixed our two affected TVs (see the uniformity photos below).