If the only output you're getting is from channel 1 then your instrument may be in Single Channel mode instead of Multi-Channel (MPE) mode. You can adjust this setting in the INSTRUMENT 1 Editor app on iOS or Desktop.

In Multi-Channel mode the INSTRUMENT 1 sends MIDI data out on Channels 2-7. For example, in Guitar and Violin modes, each of the 6 bridge triggers corresponds to one of those channels. The first trigger = Ch. 2; second trigger = Ch. 3; and so on. Be sure to route the settings in your DAW to correspond to those channels if you're trying to send specific MIDI messages to separate tracks. 

You can find more information about the INSTRUMENT 1's MIDI mapping here.