Again the infamous 'Genre' in PocketBook

After several uploads of files to PocketBook online, I noticed that the Genre is set to what is placed in the epub metadata property 'Type' (why? — I have no idea, because this property is not meant for Genre).

See: attached images

• metadata editor (Sigil.app) → notice the Type as History
• and PocketBook Online Genre → notice the Genre as History

So — I’m trying to embed the metadata property Type (dc:type) in epub files using Calibre, but I’m having some trouble. I can’t seem to edit this epub metadata property, and the Calibre custom metadata doesn’t seem to be included in the epub file itself.

Does anyone know how I can do this? :help:

Note: The idea of metadata plugboard might work somehow, but not when I'm uploading the epub file to PocketBook online.

Attached Thumbnails