Can't use huge percent of my iTunes purchased music with Photos slideshow

I am doing a slide show in Photos and despite everything I have read that says that only a small portion of iTunes content is prohibited from use with Photos, a huge percentage of my music (old new and recently purchased) is not available. I have talked to apple support multiple times and not having digital rights is the only explanation they can provide. Has anyone else encountered this? Anyone found a work around? They should denote this in the itunes store with an icon so you know not to bother buying.