Instead of asking a question, Iāll just say what I did in comment-style.
Converted tons of audiobooks to 44100 WAV
loaded SD card
only 2 worked for a minute
decided to fix it
used VLC to convert them
VLC worksā¦
reload card
audiobook audio is missing from files again
stopped working on computer
what is happening
reconverted a different way
all files play 20secs
confused
Fin
Iām guessing there is a limit beyond 100kb of storage?
I was still having OS loading issues then. However, canāt tell if it was file sizing or the USB project.
At one point I even got an entire 100mb to play.
Guess I have to choose my chapters 
It seems there might be a limitā¦ I have one 30min working.
Itās weird, because there are a few 4min songs.
Now that I look over this projectā¦I realize I spent an entire day of time trying to write nonstop to a tiny SD card. Lol
Only upload one at a time, folks 
Oh, well, we have a conclusion then! 
Get a bigger SD Card maybe? That may fix things!
It was fixed, and then it mysteriously deleted 2/3 of the books again. One read is all it took. Music wavs never do thisā¦so I thought it was super strange that a large file makes a difference. Itās 10mins in difference.
My final conclusion is that the card and phone software can only handle one 30 minute chapter of one audiobook.
I will not be appending this conclusion because arguing with this science at this point would be pointless. Iāve tried everything to get two to run, but the last 5 minutes always fail. It will also do mysterious things if you fill it will too much music too. 3.5 of our cards are unused. Idk where the computer gets what in all of these statements. You would think it doesnāt matter. Jokes on us for trying.
Sorry to hear about this failed experiment.
It is just maybe too much memory for ESP32 to read at once. Weāve never tried such things with that big files - audiobooks never came to our mind! 
When I see Ringo/any āphoneā, I think MP3 player.
When I see a screen, I think video.