As pointed out by Andrew, I had altered the rules to remove the word "each" when talking about the point card discard pile: there should be only one discard pile for point cards, and one each for each of the coloured number cards:
(a) "For each colour of Number card (including End cards), and for the Point cards, there should be one discard pile on the table – meaning up to 6 discard piles are possible."
