Here's something you can try. Connect the phone to your PC, copy everything on the SD Card to your computer. When done, reformat the SD Card from the PC then move everything back to the SD Card. Could be a formatting issue with the new OS and SD Cards making it so they caren't being accessed.
I was kinda hoping that wasn't the problem which is why I was asking if a second SD Card worked. If the second SD Card didn't work, then your most likely a victim of the post you quoted.
@ smotrs - I found a related issue in another sprint discussion:
Have you noticed any issues with your evo knowing the path to your music or pcture files on you SD card? Mine has lost it. Shows the card, and that it has memory. I can access it via the usb port, and everything is still there. It is just that my phone does not know the path/where to look? Very frustrating, as I travel a lot and listen to music/watch video on the plane. I prefer not to have to use wi-fi, since I have the storage capacity on the sd card anyway.
Took mine to the Sprint store, and they were unable to fix it. Gave me the instructions on how to reformat the card, but that is not really what the issue is, since the phone "sees" the card. I did reformat and re-install, but the phone still does not find my songs or vids. Oddly enough, some programs are still working on via the sd card, and are able to find files stored there. It is just the Music and Camera programs that came with the phone that will not access it. I have tried installing another player, and it cannot find the music files either.
I am certain it is not the SD card, because I can access my SD when I hook it up to my PC. And I can access all the music saved to my SD, thru my phone and listen to music. The issue has to do with the storage. When I tap phone storage, I can only access Apps. I can access any the other folders (music, photos/video/, other. Also, if I go under setting then apps, I can move apps from phone to internal storage. Which I am assuming is the SD card. Does any of this make sense? Any other suggestions?
Have you tried a second SD Card? I'm wondering if somehow the card got corrupted. Specially since you can't transfer to/from now.
Before when I plugged in car using usb and selected mount drive, it would recognize the music on my sd card and play the music. But now, it does not. But I think the sd card issue is bigger then we think. When I go into the storage settings on my phone...I can't move anything to the sd card, and I can't view or open the sd card storage. In the past I could. I could music or any other files/apps from phone to sd, and vice versa.