I have to say, transferring music to my Lumia 820 is a real pain in the neck.
I had an 8Gb class 4 card when I got the phone with music already on it from my previous Android device, and when I put it into the new Lumia, it worked just fine. But it had the original droid folder sctructure so I formatted it with the phone and I haven't been able to make it work ever since. I was able to sync music to this card but no matter what I tried, I got duplicate files. Browsing the forums the safest bet seemed to be getting a card reader and skipping the phone doing the sync itself.
Now I bought a bigger card, it's a SanDisk Ultra 32Gb MicroSdhc card and no matter what I do, I can't sync my music. I copy them over but when it's finished, the music+videos app says there's no music added, everything's just empty. Same with the videos. The card is formatted to FAT32 with 32K allocation unit size, I've tried to sync it with the WP desktop app, copy them in Total Commander and drag and drop them with File Explorer. I've tried formatting the card multiple times with the phone itself and on the PC, no improvement.
I seriously don't know what to do, have I just bought 32Gbs of storage and can't use it properly?? The funny thing is, Moliplayer can see the videos AND the music just fine so it's not like the card is totally incompatible, only the music + videos app doesn't see anything and if I download some new music player they don't see any songs copied onto the phone either.
Do you have any ideas? I'd really like to make it work, but this is getting ridiculous.