It is was created in a third party app then it may have no metadata and currently be listed with a song name that matches the filename, without file extension, and otherwise be listed under Unknown Artist/Unknown Album. Once you are able to identify the track in Music you should be able to convert it. Note you say that you know it got imported, but how, if you cannot find it? Music will silently reject any file it doesn't like. These can be non-standard formats, or a format that doesn't match the file extension. The way to check for certain is to drop a copy of the file in the Automatically Add to Music folder in your media folder. Either the file will be absorbed into the library, or it will be moved into a Not Added subfolder of Automatically Add to Music. It won't tell you what the issue is, but at least you will know for certain there is one.
Alternatively see https://www.mediahuman.com/audio-converter/ for an audio conversion tool that works independently of the Music app.
tt2