GIMP 2.10.8 in Ubunut 18.04 fails to write keywords correct

In darktable I put some keywords into the file, book, books, paper. I export it to jpg or to Tif.

In GIMP I import the jpg and I goto Image>metadata editor. The keywords book, books, paper are still there. When I export the file to jpg the keywords are gone. What have I done wrong? The export menu below is in Swedish, but you will recognize Save Exif-data, Save XMP-data, Save IPTC-data.

IMG_2901.CR2 (25.3 MB)
IMG_2901.CR2.xmp (3.4 KB)