Audiobook limits?

My ID3 tags are well organized.

I did find the problem with the tracks being dumped into the “Unknown” book.  The author, and the name of the folder the tracks were in, was “Pema Chödrön”.   Note the ö character.  When I changed the spelling to use just the letter “o”, then the titles showed up properly.  The Fuze apparently has some restriction on character sets that causes this problem.  So that means I am required to mis-spell Pema’s name for the Fuze to be able to handle it.

In the book with jumbled track, the tracks are not sorted in track number order.  The track number is of the form “Cnn” where “C” is the disk number (1 to 7) and “nn” is the track number on the disk.  Track numbers run from 101 through 701 using this numbering convention.  Artist, Album, Genre are all consistent throughout all tracks.  (I’ve seen sorting problems before if the genre is not consistent, but that is not what is happening here.)

Are there any restrictions on the number of tracks, maximum track number, or anything like that?