Why does my Fuji GFX100 lose AF accuracy on dimly lit night markets despite using the 32‑64mm f/4? (Seeking fixes)

I'm at my wit's end. Spent a weekend in Marrakech, hunting that perfect ambient‑light market shot with my Fuji GFX100 and the 32‑64mm f/4. I set ISO 6400, 1/30s, f/2.8, expecting the on‑chip AF‑S with 553‑point coverage to lock onto the lantern‑lit faces. Instead, the focus darts all over – half the frames are mushy, half are completely out of focus even though the subject is static.

What I've tried:

• Switch to AF‑C with single‑point, still flakey.
• Use AF‑M manually – only works if I pause for a solid second, which defeats the shot.
• Adjust focus‑assist lamp – doesn’t fire at all in low‑light mode.
• Enable the “Dynamic Area” mode, hoping the system will pick the subject – no luck.

Meanwhile the histogram is constantly clipping the shadows, and the 16‑bit DNG workflow I'm using to retain highlight roll‑off is turning into an exercise in post‑processing salvage. I’m also seeing ghosting on the Zeiss Batis 25mm f/2 when I switch lenses – the GFX sensor’s anti‑aliasing filter is apparently a factor?

Anyone else run into this combination of low‑light AF‑hunt and the GFX’s massive sensor depth‑of‑field roll‑off? I’ve read forums suggesting firmware 3.0b5 improves low‑light AF, but my box is stuck at 3.0b1. A firmware flash seems risky, but maybe it’s the only route.

Looking for concrete advice – settings tweaks, firmware recommendations, or even a work‑around gear setup that actually lets me capture the scene without endless focus hunting. I’m not interested in “just use a flash” – that kills the vibe I’m after. Need a practical solution now.