Between April 2017 and July 2017, members ViVi, Kim Lip, JinSoul, and Choerry released their single albums, continuing the same "Girl of the Month" pattern. In September 2017, three members, HeeJin, HyunJin and HaSeul, auditioned for JTBC's reality show "Mix Nine"; HeeJin and HyunJin passed the audition stage making it onto the show, where HyunJin placed Top 18 and HeeJin placed fourth in the finale. The group's second sub-unit, Loona Odd Eye Circle, consisting of JinSoul, Kim Lip and Choerry, released the extended play "Mix & Match" and its single "Girl Front" on September 21, 2017, and began promotions on Mnet's "M Countdown". The English version of their song "Loonatic" was released on October 23. On October 31, they released a repackaged version of the extended play, titled "Max & Match", with three new songs including the single "Sweet Crazy Love". "Mix & Match" and the repackaged version peaked at number 16 and 7 respectively on the Gaon Album Chart.