Several years ago I collaborated with a friend on two songs, where we incorporated a couple of my instrumental tracks into the songs, together with his vocals and other elements. I had sent these instrumental tracks to publishers before our collaboration. He then registered the new songs with SACEM in France.
Now he’s having issues with these two songs: one of them is triggering a Youtube Content ID notification (my instrumental was entered into the Content ID system by Indie Tracks); and the other is being rejected by Apple (my instrumental was added to Apple music by Audiosparx).
Maybe Art can weigh in on this as he’s good at this stuff but I had two experiences with this so far. In the first case since I knew the library had to be Audiosparx, I contacted them, told them the issue and what song and in a matter of hours or a day maybe, they whitelisted the track and there were no further issues. In the other instance, I wasn’t sure which library had entered the track into Content ID so I had to request a copy of the claim from the people who received it and it showed the info I needed to determine which library put it into Content ID and requested they whitelist that track and that seemed to do it. Hope this helps