How to find phantom songs on iPhone

I was doing some housekeeping on my iPhone, and it tells me that I have 13 songs on my phone. Thing is, I don't. The music app has nothing downloaded. I have confirmed this by looking in the music app and filtering it for only showing downloaded music.

I am not a subscriber to Apple Music, but I do have the iTunes Match thing going on.

I thought perhaps it might be one of the other music apps I have on my phone (Amazon Music or Google Play Music), but neither of them store songs that way - it's all local cached stuff to those apps.

So where are these 13 phantom songs? Is this something I can only get rid of by restoring the phone? I really hope not.