With my newly updated copy (v7.2.1), yesterday I imported all my new X-T1 files. Because I've been having trouble with the correct display of capture time with files saved to an SDXC card, I checked C1's interpretation of capture time and all is well.
Today I looked at the image folder from the command prompt to see what times were recorded. I made no changes to the files, just inspected them. I closed the DOS window and when I opened C1 I found that the files in that folder were now shown as Offline, and many had been replaced by the ! mark. Fortunately I've done no work on them yet, so I deleted them from the catalogue and re-imported. All is now well, but it does nothing to build one's confidence that the system is robust.