Sorry for the late reply!
Music Studio runs fine on the new iPad Pro 3rd gen. (12.9" and 11") models.
The only known issue is that using IAA (Inter-App Audio) instruments or effects can lead to crackling (or the tuning being off), because the new iPad Pro models only support 48kHz internally. The workaround is to connect audio hardware, then the iPad Pro will allow 44.1kHz which is the default mode of Music Studio.