I am having the same problems.
I moved mp3 songs to my SD card (music) folder but they won't show up on my android not even on the SD card when it is loaded in my phone. They show up on my SD card while it is my computer.
If I connect the phone to my car the songs show up and play just fine from a folder. Still I cannot find them on my phone or my Sd card when it is loaded in my phone.