NASHVILLE, Tenn.—Maren Morris and Chris Stapleton are the leading nominees for the Academy of Country Music Awards, but only Stapleton joined the all-male ballot for the top prize of entertainer of the year. The academy announced on Friday that Morris and Stapleton both had six nominations ahead of the April 18 awards show, which will air on CBS from Nashville, Tennessee. Women were left out of the top category after Carrie Underwood and Thomas Rhett tied for entertainer of the year last year, the first time ever for a tie and the first time a woman had won the category since Taylor Swift in 2012. Also nominated for entertainer of the year are Rhett, Luke Bryan, Eric Church, and Luke Combs. This year, Morris’ crossover pop hit “The Bones,” was nominated for single of the year and earned her two nominations as songwriter and artist for song of the year. …