I've done this a few times, but 2 instances stuck in mind:
1 - with quite a small team, where one 'team member' assumed the role of knowing everything and completely divided the group via being a smart arse. It actually ended up being very destructive long term, not great at all.
2 - was a session facilitated using visual cards which worked fairly well. We had this large pack of cards with tons of different pictures. It allowed the group to start preparing the statements by selecting pictures that visually represented how the various groups in the event thought the organisation could ideally be like. That was then used to prompt words that could be used to generate the statements. There was a lot of mixing of ideas as well by making the groups rotate around each others outputs to ask questions and also contribute ideas. Then everyone got to rate both pictures and statements produced by simply voting on what was produced by adding stickers to what you liked ( you each got a sheet of sticky dots and added as many as you wanted to each thing you liked). It worked really well to bring the wider group together (about 40 people), and resulted in multiple statements that could be considered further. I would use that process again.
I'm sorry to hear your session didn't go well. It sounds like the facilitator failed to facilitate.