This song cannot be opened

Okay, so I’m using the iPhone 6 and the app wouldn’t open up for me at first. I would start it up, the screen would go grey as usual and then just go back to my home screen. I attempted a few solutions and nothing was working so I was going to have to reinstall it. I was worried I’d lose some projects so I copied all of them from iCloud storage where they were kept and transferred them to my phones storage. When I got the app back and installed I opened all my projects with no problems except for one. I might have copied the file or moved it somewhere else but is there an easy way to find out why this one particular song won’t open?