UR28M with Logic Pro can only output to MIX2

I usually using UR28M with Cubase 8 Pro and no problem, all three mix work fine.
But I have a Logic Pro project, and I need to use it with UR28M and output three channel at same time.
(two channel for backing music while one channel for metronome, for live performance)

so what I did is set music track output to output1-2 and set click track (it’s an audio track too) to output,
but no matter what output I select, they all come to mix2, I can hear output 1-2 and output 3 at mix2 while mix1,3 have no sound.

In Cubase, those output channel have specific name like “UR28M MIX1 L”, but in Logic they are just called output1-2 and no matter what output I select, it all come to Mix2.
Is this not possible to use three different mix in Logic? any other interface will do this easily!

This Logic project is too complex to rebuild it into Cubase, so I need a solution to use it properly with Logic, please help, thanks!