I was wondering why my WD2Go app in my iPhone 4 running iOS6 (or 5.x - same thing) oddly didn’t show the files within a folder that had a custom icon when browsing a MyBook Live NAS. The custom folder was created on my Mac and I dragged it onto the NAS directory.
In fact, that was the problem, --THE ICON!
Deleting the custom icon didn’t solve the problem and I had to create a brand new folder transferring the files from the older folder (with the custom icon) to the new one.
Interestingly, this issue was not present when connecting from my Samsung Galaxy II running Android 4.x
HTH.
Dan