<$pageGroupTitle> does not work everywhere?!


everywhere in my book is the chapter title (here: “4.4 MARKETING, VERKAUF UND PREIS”) also the title which is written on the top on the right side.
But on the attached file I see on the right “4.3 Ein Blick auf die Selbstversorgertendenzen”

Any idea what I have done wrong right here?
Or is it a bug?

Thank you and best regards,