Interactive Books - Navigation

Hello,  I created several interactive books to share video playlists. I'm having an issue with the navigation menu's (table of contents) appearance. Ideally, I would like to remove the subsections, but there does not appear to be a way to do so.   All of the interactives are configured in the same exact manner from what I can tell. All interactive books contain a video with embedded multiple choice questions—no additional pages are included. Yet, the navigation/table of contents in some interactives includes subsections while others do not. I understand that subsections are autogenerated; however, I'm unclear on why the subsections show up in some interactives but not others despite having the same setup and settings.   To address this issue, I have tried rebuilding associated questions, but the subsections remain. I also tried eliminating H2 and H3 headers, but that also did not work. The subsections only disappeared after I removed the questions.   Do you have any tips or suggestions for addressing this problem? Again, it would be nice to eliminate the drop-down subsections altogether. Thanks in advance for the help!