I had the same problem. I used Reaper to record my audio but every time I would record I waoul see no waves at all. It just came up as this straight line the whole time as if it was muted while recording. I would play back and if I turned the track up almost all the way I could faintly hear something being recorded. Even if I turned up the db on POD farm and everything. Now these other suggestions could be better ionoz but I just went to the recording section of sounds on my computer and your interface should be listed on recording devices. Just double click it and go to the levels section. Turn up that level till whatever is necessary for you and yeah. That worked for me. The audio going in was apparent when I did that and not completely silent!