24 bit recording in MainStage 3.1

When I record in MainStage 3 and I check the file it always says it's a 16 bit recording. Does anyone know how to have MS 3.1 record at 24 bits? MainStage is listed under Pro apps so I'm assuming this is possible. I'm using a Duet IOS for input. If I record in Cubase I get a 24 bit 96 Khz recording. If I try to play the file back on the Mac it works fine. Why is MainStage insisting on recording at 16 bits?