with this configuration, the recipe should create 3 or 4 new book entries:
a) Beilage (1 pdf file, not in every edition)
b) Magazin (1 pdf file)
c) Zeit (1 mobi file and 1 epub file)
d) Zeit (1 epub file)
You might want to enter 'tags:Zeit' into the search bar in order to find them all.
Calibre shows the book formats in the 'Book Details' section of the graphical user interface.
Please confirm that this is what you get. If so, it would seem to me that this is a general issue of your calibre configuration and not specially related to the recipe. Have you tried sending different mobi files obtained from other sources? Does it still send epub? In this case you should post your problem on the Calibre - Devices forum.
Anyway, this is what I would do: take book entry c) and send to device. It should send the mobi file, since you set calibre to prefer mobi output. If it still sends an epub, delete the epub file in book entry c) and try again. If it still sends an epub, then I have no clue. I am not using mobi files, so I cannot test.