This is really confusing me. I am creating a document using EB Garamond Regular. I have just edited a section to italicise names of film, etc., changing those terms to EB Garamond Italic in story editor mode. When I save and close, the text appears without any italics. I've checked a few times now and the relevant terms are still showing as EB Garamond Italic in story mode. Much confused!!
Did a quick test here and got the italic font showing in the document after reloading.
Now let me make sure I understand what you are asking about. The italics are not showing in the document? or the italics are not shown in the story editor? If the later, it's because scribus uses one font and style that is set just for the story editor.
Let us know which it is.