Thanks Coldrampage, but to be clear: in my case the songs *used* to work when I first added them and now they've disappeared. So unless something changed their appid unknowingly, I'm not sure why they're gone now.
I'm having the exact same problem and haven't been able to solve this. I guess I'll need to take the time to do a full uninstall/reinstall and see if they come back when I re-add them.
Patch doesn't work for me. Running Catalina and latest Rocksmith. When I apply the patch, it says everything went ok, but when I try to launch Rocksmith I get an error about it being broken and can't launch. Any ideas what to do? What were the exact steps others took to get it working?