Vanishing files

The other day I plugged the SD card from my VS-100 into a USB card converter-interface. Just a simple little card accepter with multiple slots for different cards. There were 7 wav files on the SD card, they showed on the drive where the card was. I selected the 7 wavs and attempted to drag-copy-move them to a folder on the DAW. They disappeared from the SD card but did not transfer to the folder in the DAW. I got a pop up notification saying they were no longer on the SD drive. I right clicked and got a limited menu for actions. One of which was undo copy, but no paste. The wav files are nowhere to be found. There was no active material to paste from the clipboard and the SD card was left with some un-open able files. I could swear I'd used the card interface before to transfer files. I don't know what happened. Anyone encounter this?