I'm running the newest version of CW and have seen this issue in previous versions.  I have a file with 33 MIDI tracks.  After composition is complete I insert an audio track and render to the piece to audio.   If I am satisfied with the recording, I mute, archive and hide all of the MIDI files so I can focus on post-production issues and wave file enhancements.  When I save the file and re-open it, all of the hidden tracks, except the last one (#33) are visible.  It doesn't matter whe