What is an example of polls being an inaccurate in determining policy?

Many polls saw queries on the Labour stance on trident as it was vague in their policy and whether Jeremy Corbyn would ever use nuclear weapons. The party and the leader never clarified on this and continued a very anti nuclear weapons Stance + it Arguably it was the Labour manifesto in 2017 that changed views on public spending and shifted the opinion poll and not the other way round.