f8lee

I too have that lens but have not seen this behavior - I'm replying to see if others have answers.

So I discovered this this morning...
I shot an event on Saturday, taking my X-T3 and X-T4 and some fast Fuji glass. Turned out the 16MM f1.4 lens would not auto focus on the X-T3 though it was fine on the X-T4.
Well, today I learned that this was my own fault - I had inadvertently pulled the focus ring backwards to disengage the auto focus clutch, so that answered the question as to why it didn't auto focus on the X-T3. And I have to thank the tech at Fuji - I called this morning to ask about this and he asked if the focus ring was disengaged...
But - and here is why i am posting this here - that same lens set the same way DOES auto focus on the X-T4! It's as if the X-T4 body just ignores the setting on the lens - and that was something the tech (and the other ones he asked about it) never had seen before.
So those of you with that combo - give it a try - it's just odd.

Can't wait to get mine (having had the 1, 2, 3 and 4) - I see there will not be a battery grip made available but I guess that's because a single battery can give pretty amazing performance in terms of burst speed  and number of shots taken.

Just a guess, but is it possible you sometimes take photos with the camera pointed (more or less) straight up or down? I have found the X-T cameras (1 through 4) have all on occasion gotten "confused" as to photo orientation when I do that - say, pointing straight down at a flower or something.

Reading this thread, I wonder what the fans of C1 think about their subscription program (same as Adobe at $10month). I presume that, like Lightroom, the subscription approach will assure one of having the "latest and greatest" version as opposed to site licensing that generally implies additional payment must be rendered for the next full version upgrade.
Meanwhile, a question - does C1 offer the facial recognition capability that LR does? Having "taught" my LR across the 30K images I have, now if I want to call up all photos that include my brother (for example) it's simple to do. Looking over the Capture One site I do not see this function mentioned at all.
FInally, don't know if anyone has heard of or tried Excire Foto and Search - a new program that uses AI based image recognition to assign metadata to images. ("Foto" is standalone; the "Search" add-on is the plug in for LR). I did but it a couple of weeks back and can say it does a pretty impressive job. No individual facial recognition (thought it determines if there are one, two, three or more faces and whether they are smiling or wearing glasses) but, while not perfect, pretty impressive auto recognition of architecture, a variety of animals, etc.
Having heard good things about Irident I am going to give that a try, though frankly I have been pleased with how LR (on my Mac, if that matters) has handled the .RAF files.

Are you using a lens with OIS?  If you are, turn image stabilization on and off with the lens.  
 
If you put a lens on the camera without OIS, OFF will suddenly appear in the menu.