I'm having the exact same issue in 4.6. From the song, I intentionally lowered the volume to test it and then updated the mastering file. In the Project Page, the waveform correctly shows the lower volume and the loudness detection works as expected, but the volume does not change until like 15 seconds into the song or toward the end of the song. If I locate the actual mastering file, the wave file plays fine in other apps. It even plays file if I use the browser within the Project Page to preview it. So, the file is getting updated. There's a problem with the Project Page. Creating a new project or adjusting the START & END flags on the song page did not work for me. I have tried creating a song with just a wave file and no plugins to rule out plugins. Switching to the built-in audio did not work. I also did a complete reinstall of the S1. I downgraded to version 4.5.5 and the Project Page is working correctly.