Creating audiobooks from individual tracks

I have the following audiobooks in the latest iTunes under Windows 10:

1. I have imported several audiobooks from Audible into iTunes. Each book appears under "Audiobooks" on my iPod Classic as a single entry.

2. I have also imported several books purchased elsewhere, as individual MP3 files. I have ensured that the title, author, etc. are identical and have numbered all tracks correctly. I have set the Media Kind to "Audiobooks" and have selected the "part of a compilation" option as well as the "skip when shuffling" and "remember position" options. In iTunes, these books appear correctly, each as one entry, with all the tracks in the correct order.

3. I have also imported one original CD audiobook (11 disks) and have curated the meta-data as described above. Again, in iTunes, the book appears correctly.

After syncing to my iPod Classic, all the Audiobooks appear, but only the Audible ones appear as a single entry per book. Each track of each of the MP3 books and the CD book appear as individual entries/books. This makes for a very long list, and, of course, makes it very inconvenient to listen to. I would have to scroll to "Chapter 1" of the book I want, listen to it, and then scroll to "Chapter 2" of the same book, etc. "Chapter 1", "Chapter 2", etc. for each book appears in the audiobook list.

I have searched extensively, but have not found a solution. This answer did not solve the problem I describe.