On another forum someone suggested spraying some electrical contact cleaner into the wheel but the Fuji tech said that could risk frying the rest of the cameras electrical so I haven't tried that.

I have an x100VI with 1.01 firmware - did a reset already and didnt solve issue I am about to describe. Can you all see if your camera does this: Switch to C mode, step down to f16 and then press shutter half way. Does your screen go dark? I have tried playing will all settings (have had the following so quite familiar with the menus: x100, x100f, XT-2, X-Pro 2, XT-3) , only happens in C mode. If you find this can you report to Fuji @ digitalinfo@fujifilm.com. They told me they had not seen this before and that it was normal behavior because the shutter is closing, but the shutter closes in S mode as well.

That’s a common problem with many cameras, filters irritating the autofocus.

I can't vouch for the Sigma on the X-S20 but I do have a Viltrox (27mm f/1.2) and the startup speed is identical to when I have the Fuji 18-55 on it.

I have focus error issues when I placed a VU filter on the X100VI. Only on close up macro photography. The filter is placed backwards because of the threading. When I take the filter off the camera the focus works properly.