I have a year old A4 with an SD card reader. However when it won't display all the albums I've loaded on to the 32GB HCSD. It should have 130 album folders but only shows about 40. I even bought a new card and tried a windows OS rather than my Mac, but no change.
Do you have more than 4000 files (music or not) on it? I had this problem and solved it by deleting everything that didn't have a .mp3 extension, including ask the hidden files.