Okay, this is getting ridiculous. I copied the files via a USB cable, which took a couple two to three hours. After that a lot of songs wouldn't play, even if I tried to play them on my computer, but in their original location on the computer, they would play. The files appeared to be the proper size and nothing else appeared wrong, but now going back many of those files, including ones I never tried to play. have totally disappeared off the SC card. And the free space reported on the SD card has increased by about 10-15 GB.
This is the card: Amazon.com : SanDisk Ultra 64 GB microSDXC Class 10 UHS-1 Memory Card 30MB/s with Adapter SDSDQUA-064G-U46A : Electronics