Last week, after the ICS upgrade, I tried copying a dozen tracks from one ripped CD to my SD card, and only 3 showed up when I tapped
My Music > My Library > Album Name
So I repeated it with a different Album, and got the same results. I then connected the Droid 4 back to the PC using the USB cable and it showed, in both cases, all 12 tracks!
For what it is worth, I used this same procedure on another album before I converted to ICS and had no problems: all tracks are available for playback on that album.
So, via USB cable it shows all the tracks in each album; via My Music > My Library it only shows three.