SIOUX CITY — A tentative settlement has been reached in a lawsuit filed over nearly $1.8 million in unpaid revenue-sharing funds from the former Argosy Sioux City riverboat casino. Attorneys notified a U.S. magistrate last week of the tentative deal. The terms have not been disclosed. The nonprofit Community Action Agency sued the Belle of Sioux City, which operated the Argosy, and Belle’s parent company.