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In MAD - MassCore mode, the bridge channels are pure virtual channels, and cannot be routed to the MassCore mixer.
Those virtual channels are designed to connect third party ASIO applications between them ; e.g. a soft synth audio is routed to a MIDI sequencer - ASIO application, then routed into PMX Mixer.
Rewire Mode
MAD MassCore mode and Rewire Mixer mode cannot be used at the same time, as both use the same MTASIO Bridge.
If you need to run MassCore with Rewire Mixer mode, please change the MAD running mode to RAV/AES67.