The top dials all being in ‘Auto’ are probably acting to limit your options. Try manual settings re:
https://fujifilm-x.com/en-us/quick-start-guides/quick-start-guide-fujifilm-x-t3/
scroll down to the Shooting Video section and give those options a try. Keep in mind the note about f-log files needing color grading.
edit: p.s. If you are curious as to how to get the 1 / 48 shutter speed, this video explains how to do that as well as some other stuff:
NewbieCAM got a reaction from jerryy in Fujifilm Xt-3 Exposure Settings - Not able to adjust exposure in video mode.