Just for the fun of it I also tried to fix the order of audiobook tracks with a FAT sorter. It worked fine for me. I did not use your trick with the manual transfer, because I’m convinced that it will indeed work. However, if one has to do the sorting manually file-by-file it would take a big chunk out of your day every time that you would like to upload an audiobook. Perhaps we can understand why it did not work for you if we compare the steps that we have taken? Here is what I’ve done
-> I downloaded a random audiobook from the public domain (in order not to breach copyrights …). This audiobook contains a separate mp3 file for every chapter (all below 20MB):
where the <some_text_123> is the same for every mp3 file.
-> I manually copied (some of the files) one-by-one and in the wrong order to the Audiobook folder of the player. Disconnected the player and verified that indeed the tracks were in the intentionally wrong order.
-> Reconnected the player and applied a FAT sorter (not FatSorter or DriveSort, but a similar tool). Disconnected and then all tracks were in the correct order.
Did I do something differently from what you did?
BTW, what puzzles me from your description is that in your case the same random order occurs before and after applying the FatSorter. To me this suggests that the FatSorter did not run on your folder at all. Would it be possible for you to verify that FatSorter actually did anything? What if you apply it to another folder, such as on the Music folder? Does it work properly then?
BTW2, the above applies only when viewing the audiobook from the Folder menu, since in the Book menu the ID3 tags are used for sorting. I suppose that you were referring to the Folder menu as well?
… Hope this helps. Cheers