Hi this is my first thread here so I hope I make everything the right way.
So here is my problem:
I try to record my guitar with the Axe-Fx II XL. The hardware routing is as follow,
guitar → axe-fx → S/PDIF → Steinber UR28M → USB → Computer.
When I don’t start Cubase I have sound and can play my guitar. The UR28M is set as slave (get’s the clock via S/PDIF from Axe-fx). The Axe-fx runs on 48khz. So everything’s fine.
Now I imported a midi file into Cubase and added a new audio line for the guitar. So now the importent part! When I play the guitar now I see that Cubase gets an input, but there is no output (cannot hear the guitar). So when I click play I hear the sound from the midi lines. When I click record and play the guitar, it records it and afterwards I can listen to it (well it’s just noise becuase I can’t hear what I play while recording).
I checked the VST routing many times and the midi lines and the audio lines have the same output busses but it doesnt work. 
Can anybody help me with this problem?