keywords cant be written in IPTC and XMP

[viewfan]

I can not write keywords anymore in (Ctrl+I). Neither in All nor in one.
The other data's working... it seems keywords are different from the other IPTC Data's.

After writing keywords there is then a tab XMP (in file propertis > Alt+Enter) but this is empty, so some thing changed in the file but no keyword data written...

I am using for the first time the new Version 0.96.4 64bits MP on antiX Linux (Debian).

[xnview]

you choose a jpeg file, 'IPTC dialog', enter some keywords and write?

[viewfan]

you choose a jpeg file, 'IPTC dialog', enter some keywords and write?

As you wrote "...and write", I saw the first time now (I use the Dark Theme): There is a little triangle next to the vertical triangle and there a keyword has to be chosen from one of the other datas which exist in the file already. But 'writing' an individual keyword is not possible but it can be taken over from 'Description'.
(German) schreiben in Schlüsselwörter nicht möglich aber in:
Objektbeschreibung > Feld Objektbeschreibung

And all works only for one file not for multiple selections. Also the Keyword is not imported as Kategorie when in settings Metadaten XMP-/IPTC import as category.
(German) : F12 > Metadaten XMP-/IPTC-Schlüsselwörter als Kategorien importieren.

I mention this as it happened sometimes that I had suddenly a new Category which came obviously from a keyword in a downloaded file from the web.
My Idea was after that to take over Categories from an old system by writing in multiple images keywords...