newly added songs disappearing from Music library

I create songs in Logic. I create/bounce an Apple Lossless version of the song so I can then add it to my iMac's Music library, share it with my friends, add it to my phone, etc. Logic places the file in a predetermined location. When I want to add it to my Music library, I will import the song by navigating to that location and importing the song or by dragging the song file to the Music app. (Logic could add the song to my Music library directly, but I choose not to do it that way.)

When I import one of these files, I use Get Info to fill in the metadata since Logic doesn't add much. I import the song, add the metadata, add a photo for the album artwork and add the new track to a playlist. I then sync my phone so that the new track will be on my phone. Sometimes I share a copy of the song (they are small) with my friend via Messages. I do this after importing the song so that he gets a copy that includes the metadata and album artwork. Thus, I grab a copy of the track that iTunes added to its own Media folder.

I just did this whole process today and yet again, the song disappeared from my Music library. When I originally imported the new song, it appeared at the top of my sorted Songs view. I used Get Info to edit its metadata. Once I was done, I went to the Media folder for Music, found the track there and sent a copy of the song to my friend. So clearly, I was successful adding the song to my Music library and updating its metadata.

I then plugged in my iPhone and synced it, expecting the new track to be added to the phone. (I do not use the iCloud Music Library.) But the new song did not get added. When I went back to Music, the song was not there, not at the top. It was not in the playlist either. I tried searching for it and tried navigating to the album it was added to. Not there. I went to the Media folder and the song was still there. The only way songs get there is if the Music app puts them there. So I had to import the song again, this time by navigating to the Media folder. Ridiculous, I know. The metadata and artwork were still intact. And now the song is finally in my Music library. And I was able to sync my phone again to add it there.

What is happening here? Why do I struggle to add my own homemade songs to my Music library? Why doesn't it work the first time? Is my Music library corrupted somehow?