I've found an acceptable workaround until this is fixed:
In the content pipeline, convert all the music files from
SoundEffect. Then load music as a
SoundEffect, create a
SoundEffectInstance from it, and play it that way.
SoundEffect backgroundMusic = content.Load<SoundEffect>("ogg/" + name);
currentMusicInstance = backgroundMusic.CreateInstance();
currentMusicInstance.IsLooped = true;
currentMusicInstance.Volume = 0.1f;
Using this method, the entire track plays and loops flawlessly. The downside is that this tripled the size of my project (~50 MB to ~150 MB) since the music files are no longer compressed ogg files.