Might need a sigma upgrade. Contact them and ask. I know that some lenses need help to work in the Z mount.I just bought Sigma F mount 105mm 2.8 Macro lens and mounted it on my Zf with FTZii.
For some reason I cannot get 2.8 aperture. Its like stuck on 5.6
Is there some kind of setting that I need to switch for that to work?
Agree with this.From memory this lens aperture changes the closer the image at min distance 1:1 ratio f5.6
Please refer to table in top right of the manual