exactly, moved them to main level of the usb flash drive
meaning root, some player can't read folders
also you have 2 options, if the above still doesn't work
option #1 is by using command keys on the keyboard to make the hidden files visible
unfortunately I don't have the document here with the shortcut keys
I don't remember them right now
but I'm sure that if you look for them, you can find them
option #2 you can use a free app
https://gotoes.org/sales/ShowHiddenFilesMacOSX/How_To_Show_Hidden_Files.php
after you run the app for the first time
go to the the Botton window and select
don't show me your ad anymore
now you can close that bottom window
now in the main app, click on show special files
after doing that you will be able to see the hidden files and folders and you will be able to delete them
to revert back or to hide the files simply click, hide special files
now the system is back to normal
hope this help
[doublepost=1551478410][/doublepost]are you mp3 files in 44,000 or 48,000?
did you read the CD player manual and check what files are compatible?
there are a few things to consider here
bit rate
I recommend 320
maybe your mp3s are in 128 or probably even less that's why there are not being recognized by the player
keep in mind that many player also support 128 but you have to check the manual to know for sure what's compatible
also maybe you are using a incompatible codec
Thera are a few mp3 compressors
are you using, constant bit or variable bit rate?
download a free trial of AnyMP4 Audio Converter and use that app to convert the files to mp3
make sure to select these settings
44,000
320
CBR
try another with another pen drive
some old flash drives are recognized different, specially very old and small ones
get a new one, they are cheap now
you can get a new one for less than 10 dollars or ask a friend to lend you a thumb drive
make sure is not so old
some usb thumb drives come with 2 partitions from factory and with files inside
you have to know how to reformat and repartition the drive to a single partition
best of luck
I don't think is the hidden files unless you have some hidden folders and the system is trying to read those hidden folders and that's why it fails