Progress in summary of interactive book is displayed incorrectly

When building some interactive book content (version: 1.6.9 but also the version before) the counting of the interactions is incorrectly. F.e. it is possible to get 9 out of 6 Interactions. Therefore the interaction progress is also incorrectly (150%).

I use multiple interactions within the interactive book: Agamotto, Drag and Drop, Accordion, Image Hotspots, Single-Choice Set, Dialog Cards, Summary. 

I guess the problem accurs because Agamottos are not counted as interactions in the beginning. But they get counted when using them. Because f.e. on the site "Farbmischung" (see attached picture) there are only 2 intereactions: Drag & Drop and Agamotto and 2 out of 1 interaction got counted.

Best regards

Bianca