What are the LR versions, the type of the files as well as the camera if they are RAW?
The majority are HDR files tonemapped in Photomatix Pro. Others are imported from other people's pictures (email attachments, WhatsAp etc). My own regular pictures exported fine.
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That does respond to none of my questions.
Versions of both LR?
Type of files (jpg, dng, tiff .., not the content like a HDR)?
Have you been working on these files in LR before trying to export with/as a catalog?
Thank you I have fixed the problem
It may be helpful for others if you tell us what caused the issue and how you fixed it.