Hi folks,
I got an official reply about the "Interlock MF assist & Focus ring" option with MF lenses.
Don’t fret, what you’re experiencing is normal. The question that would showcase why it’s not working would be:
“How would the camera know when the focus ring is moved without a way of communicating that to the camera body if there are no contacts on the lens to pass that information?”
Essentially with FUJIFILM lenses (and basically almost all new lenses from every manufacturer), moving the focus ring changes focus electronically so the camera knows when the ring is moved through software/hardware, without that, like with vintage lenses with mechanical focus, there isn’t a way for the camera to electronically know when the ring is moved, so the function won’t work as intended to turn off/on MF assist when the focus ring is engaged.