Hi. I have an entire catalogue on Tunecore and I have never been questioned. Not all of my songs are BIAB but a few are. One thing you did not mention is "are you doing an original song or a cover"? I've done my own versions of covers with BIAB (Walk On By, Ooh Baby Baby) and distributed through Tunecore. However, I secured copyright permission through Tunecore before the music was distributed. So in essence even if you're doing a cover with your own version it's still considered a copyright violation unless you secured the rights. My original songs that I wrote with the assistance of BIAB have never been questioned. Also they are vocal driven songs. I'm also not sure if your song is instrumental or not. It appears that some way your melody was flagged. I'm sure you can put in a help ticket and ask them to clarify. They usually get back to you pretty quickly. The sites have seriously clamped down on copyrighted material. I've gotten copyright warnings on my YouTube Channel for my OWN songs. Because Tunecore is also my Publisher they actually have YouTube and Facebook rights (which I granted) to my own songs. Again if you believe this is in error submit a ticket and have them explain ... or go to DistroKid .. :-)