Audio Technica ATH-M50x. Sound in only one ear? DDJ-RB

Got a new pair of headphones. Plugged them into the DDJ-RB to check them out but I only get sound out of the left ear. Works fine when plugged into other devices. Is there some setting I'm missing? Everything was working fine with my old headphones. Are there certain models of headphones that are not supported by the DDJ-RB? Thanks in advance :)