I've attempted to open several GFX images in the latest version of ACR, only to have them showing as grayscale, with no way for me to change to color...has anyone else encountered this issue lately?
Look under the Camera Calibration Tab at the Camera Profile and see if it's set to one of the Monochrome profiles.
Camera raw 9.12 includes color matching camera profiles for some cameras.
sample files from here
Fujifilm GFX Review: Now Shooting! - Gallery
Retrieving data ...