I replied to a message, last week, where someone mentioned that their camera's ISO settings would not go below 200 or above 12,800. I chimed in saying I had the same issue and had sent the body to Fuji in Edison for evaluation.
So, the scenario that limits ISO to pre-firmware involved setting the Shutter type to either ES or MS+ES. Evidently, the ES mode will only cover pre-update limits (200L and 12,800). When moving from ES back to MS only, the 100 ISO point is tecovered.
Sent from my iPhone using Tapatalk Pro