I was testing a level
I had the .ogg file in the same play as my player and editor
but it wouldn't play, as if it didn't exist
the file was called "m_stage9b.ogg" typed in "m_stage9b" and it did not play the song
i even tried adding ".ogg" and it still didn't work, I've tried others and still nothing
Custom musics (when not built into an NXP or music pack) should be in a "music" subfolder of wherever the player EXE is. Testplay mode does not change this. I have just tested and confirmed this works.
Let me know if you're still having issues, otherwise this topic can be closed.