I have a series of .jpg files that do not show on Ubuntu Image Viewer or as thumbnails. These are perfectly ok on Windows 32 and 64 and on Mac OS.
Strangely one very old .jpg file does display correctly and its thumbnail is visible in Files no bother just these new ones.
After one hair pulling exercise found some which would not display on Windows were wrongly tagged as .jpeg by extension removed all these. Now all are on …