I noticed the same with my newly bought X-T4, the shutter speed disappeared and I was not able to make it visible again.
In a desperate action to make it visible again I did a "Still Menu Reset" as suggested, and there it was. But! When I then started
to make all settings as I had them before the reset, the shutter speed was gone from the display again! By toggling around
with different settings I found that setting "Dynamic Range" to "Auto" was the cause of it all. All other setting of "Dynamic Range"
will let the shutter speed show in the display, but not "Auto"! Since I can't find any documentation about this in the manual
I will treat this as a bug.
Thoughts anyone?