I think I'm getting the same issue. When I get new photos or try to add new music, it goes on the SD card: The Other section of the SD card increases, and when I put the SD card into the computer I can see all the files. HOWEVER, I can't see these photos or music that are on the SD card on my phone, so it's pretty much 32 GB of uselessness right now. This SD card seems to have gotten more useless after the latest firmware update (on Nokia Lumia 820, O2 network in the UK)
Did you fix it and how can I do it? =/