Board Thread:Spoilers!/@comment-26159109-20150928143524/@comment-26159109-20151111051039

Two explanations I can find is either she was at the restroom (she is always at the restroom) when they got to camelot via Apprentice's wand, or Emma and Hook changed something in the past that somehow resulted in Ruby never coming to Storybrooke in any curses, erasing any canonial appearences Ruby had in S1-S3.