Rebuild embedded EXIF Thumbnail - not work

[Zipping9519]

Scenario
Can't rebuild embedded EXIF Thumbnail for some images which do not have EXIF Thumbnail.

To re-create
1. Execute : Tool->Metadata->EXIF Thumbnail Rebuild.
2. Nothing happens. The image's modify date also doesn't change.

Examples:
https://easyupload.io/0tiquc
(I guess thumbnails of these images were removed to optimize the size.)
I also tested other normal images whose EXIF are removed by XnView(Tool->Metadata->Clean), and things are same.

Expected result
EXIF Thumbnails should be added.

Actual result
They are not changed, and still do not have EXIF Thumbnails.



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Tech info
• XnView version: v1.3.1 + v1.4.0
• O/S: Windows

[xnview]

yes a known issue if embedded thumbnail doesn't exists