I am not so sure that the pollsters were wrong. The most notable thing about the polls this time is that there were around twenty five percent undecided right up to the wire. That is virtually unprecedented.
It is likely that WR supporters were all declared and very few of them would have been in the undecided. Consequently, the numbers in the poll were the likely limit; or not far from it.
Its appeal is limited to the Far Right and it is unlikely to ever reach the support it had in the election again when some of those who simply were voting for change absorb what they could have been responsible for.
Only a scenario like the federal could see them actually achieving power: a multi Party split with a few Parties all having strong support.