I don't understand why this image has no 'Date modified' value. Did anybody encounter such a scenario ? When looking at Exif tags, all seems normal. I have looked at 'image forensics' sites which do not report any issues. I discovered this problem when trying to open the image with ImageMagick, I get the error 'insufficient image data in file xxx'. The image can be read with usual image tools.
Any help is much appreciated !