IPTC tags missing in XMP output

[User654]

I am extracting from my old jpgs (embedded IPTC tags) xmps to associate the metadata with my raw files. However - it appears that some old IPTC tags (ACDSee) are not extractable into xmp.
When I run this command:
    exiftool -IPTC:all IMG_2753.JPG_original

I get this response:
    Caption-Abstract                : Sunset
    Keywords                        : Paris

However - when I try to extract them into an xmp file - I get nothing:

exiftool -IPTC:all -v5 -o IMG_2753.xmp IMG_2753.JPG_original
======== IMG_2753.JPG_original
Setting new values from IMG_2753.JPG_original
Writing IPTC:Keywords
Writing IPTC:Caption-Abstract
Warning: [minor] Canon maker note footer may be invalid (ignored) - IMG_2753.JPG_original
'IMG_2753.JPG_original' --> 'IMG_2753.xmp'
Creating XMP file...
  Error = Nothing to write
Error: Nothing to write - IMG_2753.JPG_original
    0 image files updated
    1 files weren't updated due to errors

Similar when trying to extract it explicitly - then I get the keywords - but not the Caption.

exiftool -Caption-Abstract -description -keywords -v5 -o IMG_2753.xmp IMG_2753.JPG_original
======== IMG_2753.JPG_original
Setting new values from IMG_2753.JPG_original
Writing IPTC:Caption-Abstract
Writing PDF:Keywords if tag exists
Writing PostScript:Keywords
Writing MIE-Doc:Keywords
Writing XMP-acdsee:Keywords if tag exists
Writing XMP-xmp:Keywords if tag exists
Writing XMP-pdf:Keywords if tag exists
Writing IPTC:Keywords
Warning: [minor] Canon maker note footer may be invalid (ignored) - IMG_2753.JPG_original
'IMG_2753.JPG_original' --> 'IMG_2753.xmp'
Creating XMP file...
    + XMP-pdf:Keywords = 'Paris'
    1 image files created

I assume there is probably some character encoding issue or something binary in the Caption - that it does not write the caption into an xmp... Any ideas?

I am running exiftool on windows command line - version 9.99
I am quite sure this is related to these old image files from prior 2010. When I touch them using Lightroom or a newer ACDSee (Pro5) - they can get extracted afterwards without a problem - however - its just way too many...

[Phil Harvey]

The problem is there are no XMP tags with these names.  So you need to figure out what XMP tags you want to write, and redirect the tags when copying, like this:

exiftool "-xmp:description<caption-abstract"  "-xmp:subject<keywords" ...

Actually, you will find a full set of arguments to do the standard IPTC -> XMP conversion in the full distribution.  The file is arg_files/iptc2xmp.args, and I attach it here for your convenience.

- Phil

[User654]

excellent - that was exactly what I was looking for - it worked perfectly now.
THANKS.