Can't hear guitar input unless it's recording
I'm trying to record some bass & guitar tracks with Logic 10.3.2 through my Tascam US-1800 interface.
I activate input monitoring and the record button; and I can hear the instrument through the interface and speakers fine when nothing is playing back. But as soon as I hit play back to rehearse against existing tracks, I lose the audio. I do see the meters bouncing for the input channel, but I can't hear it.
If I hit record and start the track, then I hear the instrument fine. And it records and plays back just as it should.
Anyone have any idea what I might be missing?
Thanks in advance for any ideas.
iPhone 6s, iOS 10.3