Problems displaying raw files from Fuji XT5

My partner and I both have the XT5.   Initially I couldn't preview my raw thumbnails, however, after trying various options, they are now visible.     My partner still cannot view the raw files from his camera's card as thumbnails, on his computer, or even on my computer which now shows mine.     I am now wondering if there is a difference on how his camera is writing to the SD card.    It doesn't make sense, otherwise, especially as I can't view the thumbnails of his raw images on my computer.    Any thoughts please?