This achievement is mildly glitchy. Some people have met the requirements and have not gotten it. Also, you can get this on Expert but instead you must play all the hammers without strumming since that is the Expert equivalent of the goal. Walking on the Sun seems to be the easiest on Expert, though So Watcha Want by the Beastie Boys (RB2) remains the easiest bass song in the catalogue as it is only green notes. If you are having trouble with upstrumming, turn on lefty flip for the Beastie Boys song and just down strum.