You are a saviour, been searching for a solution for this for weeks. This is worst UX from Fuji. Thanks for clarifying this, it would have never occurred to me otherwise. Thanks again brother.
Hello! I hope you've figured it out before now, but I was just looking into this setting and found your post.
This is quite odd, but when you go into settings and select the left function dial, it looks like the only options are "default" and "none." BUT, if you use the joystick to scroll down, a whole new screen of options will show up, including ISO. I just gave it a try and was able to assign ISO to that button.
No clue why it would display that way, but for some reason the first page it shows you is page 4/4 instead of starting at the top of the list.
I just wanted to let you know in case you didn't figure it out yet!
