SanDisk REMOVING files in SD card and "File format not supported" !

  1.  Is the card in the player or are you using a micro so card reader ?

I copied the files using my the SD reader from my laptop (Sony Vaio).

  1.  What software do you use to copy your files and folders to your card ?

Win 8.1 SL + Total Commander 8.51

  1.  Do you ever see the files and folders in the proper destination using Win File Explorer ?

Yes, checked before inserting the card into SanDisk.

  1.  Do you use the PC “Eject” command to stop the PC - player communication before disconnecting the player ?

Mmm I didn’t connected the player in this case, but previously (before buying the SD card) I could ejected without “safe eject” the player. That could be an issue with a SD card?

  1.  When & how do you observe your music files are missing?

        The Clip Sport cannot find them by Music Mode and Folder Mode ?

         Your PC cannot find them during a follow-up search with Win File Explorer ?

Both cases. Inmediately after the SanDisk media scan finished the files were not there anymore.

  1.  I think the Clip Sport can access high capacity micro SD cards formatted as FAT32. 

        How is your micro sd card formatted ?

FAT32

Let me know if I can check anything else.