I have seen a few comments on this forum regarding this issue, but no clear answers.
When I load audiobooks (organized into folders) MOST but not all of the folders are listed in the Audiobook section. All of the folders appear in the Folder menu. However, I want to use the adjustable speed for playback, which is only available when you use the audiobook menu.
I am not exceeding the 2000 file limit and the folders that are “missing” are random. If I delete them all and re-install them, a completely different group of folders will be “missing.”