I too have a similar problem.I have been adding dlc's to my folder and some of them work and some do not alltough I have made sure that the id's have been updated etc. Some of those songs were also rammstein etc.At the moment I have some files which on the surface seem the same but some do not work and some do, I have not managed to add any new ones either. I tried all possible configurations with different dll's etc.My dlc count was nearing 200 and since I have seen people having thousands and not have an issue, im not sure whats going on with this.