I have some bad news.
Consensus is about something you can live with, not about something you would die for. It’s not unanimity. Most times, consensus is simply an idealistic vision which has virtually no bearing on the quality of the decision at hand.
Too many of your clients (and, perhaps, you) are wasting time trying to get buy-in and commitment from people who simply don’t matter in the long run. Ineffective and frightened leaders strive for “consensus” to protect themselves. (“Don’t blame me, I asked you first.”)
Make a decision and move. If you’re an expert, that’s what you’re supposed to do. If you’re not an expert, then get out of the way.