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. 

In Windows PCs the backup is saved in  folder Documents>Fujifilm>Conditions. If you open this folder in a window before you start the backup you'll see the backup file appear in the window. It's almost instantaneous. It's a confidence booster. I don't remember X-Aquire giving any indication that backup has completed. The backup files include the date and the camera make so if you have two Fuji cameras they all go in the same folder. New backups do not over-write the older ones so you can restore an older one if you should so wish. Simon  

Hi, thanks for getting back to me. It's a shame because my X-Pro1 works perfectly except for the aperture with the 27mm lens. I think it would be better to switch to the new WR version that allows aperture changes with the ring. Thanks for your help.