Ubuntu 20.04.2 File manager doesn't show some files

Solution 1:

Everything you write, i.e. leaving a folder, changing a file in that folder (exiftool in your case) and returning to see nautilus continuously "loading", coincides with a bug report, recently filed for Files 40 over at Gnome Issues. Although reported for Files 40, I can reproduce the bug perfectly on 21.04 (Files 4.0). In my own experience, it is related to having a large thumbnail cache. Clearing the cache makes the issue go away, so constitutes a work around to this issue.

To clear the thumbnail cache, remove the .cache/thumbnails folder using the file manager or with the command:

rm ~/.cache/thumbnails

This folder will be automatically recreated as soon as an application is creating thumbnails.