Collapsing stave voices into a single stave

I just "imploded" 9 voices in 9 staves into a single stave. Then I repeated the implode on that single stave and it removed all the unwanted rests and duplications.

I'm posting this 'cos I saw a lot of discussion about that unwanted stuff and complicated ways to tidy everything up.

Sadly, what it didn't do is capture ALL notes! Some have gone missing. Trying to figure out why. Might be because it can only collapse 4 notes ('cos there's a limit of 4 voices on Musescore) at a time. So collapse 4 onto each stave, then collapse those staves together?