Hi Deon,
As discussed offline, I am sending you a few samples to swap out and see if they work. In the meantime, I'm looking at your layout, and am guessing C2 is your output capacitor. Where is the input decoupling capacitor? If it is too far from the IC, there is an off chance that voltage droop at the part is somehow setting the part to the 1 V output mode.
If you get a chance, could you tombstone a 4.7µF capacitor between pins 1 and 2 and see if that improves the situation?
Ryan