I’m experiencing an issue when recording on my Mac (10.11.5 El Capitan). I’ve recorded on this device dozens of times before without issue.
I open a new project, I hit record, a new track forms, but the pin does not move. Nothing is recording.
I tried uninstalling and re-installing and it’s the same thing.
Has this problem appeared after a Mac update? (See: Check What Software Updates Have Been Installed in Mac OS X)
I checked the updates log, there doesn’t seem to be anything out of the ordinary.
Some additional info:
-I use a Blue Yeti microphone. I happened to have a second but the results are the same.
-When I switch to from “Yeti” to “Built-in input”, it DOES record, but that’s not the sound quality I need.
That’s useful information - rules out several possibilities.
In the system sound settings, if you select the Yeti as the recording device, do you see a signal level when you talk into the mic?
It appears to be working now. shrug 
Do you do anything to get it to work? Im having the same issue, it records with the build in input but when i switch to my microphone the red recording line appears but it just sits there, recording nothing.