I haven’t heard of 12 states, but here is the 11 state list from Wild Jack’s terms and conditions page.
IMPORTANT NOTE: Due to US gaming regulations, players residing in the following states: Illinois, Indiana, Louisiana, Michigan, Nevada, New Jersey, New York, Oregon, South Dakota, Washington, and Wisconsin, are not allowed to play the casino.
Have never seen an official listing from Microgaming, but that sure would be nice.