Kim Yeon Woo and his current label Dio Music sued his previous label Mystic Entertainment. According to his previous contract at Mystic, Kim Yeon Woo and the label would split music contents 60:40, and they would split profits from other entertainment activities 70:30.
The problem arose from his 'Masked Singer' appearance. Mystic Entertainment had split profits that came from his songs on 'Masked Singer' 60:40, as they were profit from music sales. However, Dio Music argued they should actually be split 30:70, as they were from his 'Masked Singer' appearance.
The court ruled in favor of Dio Music and Kim Yeon Woo and ordered Mystic Entertainment to pay Kim Yeon Woo 131,590,000 KRW (~120,000 USD).