I have that problem as well. I haven't found a fix..but what I do is keep all my CDLC in a separate folder. I move songs I want to play to the DLC folder..let's say there's 10 songs. I fire up Rocksmith and maybe I'll see 6 of those songs. I play a bit...then go out and take out the songs I just played. 4 remaining in DLC folder. Restart game, and I may get 2 of the remaining songs show up now. etc. It's annoying, but they all work, eventually. Must be conflicts between song names I figure.