No audio going into GarageBand I just got a Blue Snowball iCE, plugged it in and my Mac recognized it fine. In System Preferences > Sound > Input, Blue Snowball shows up and is selected and I see the input level meter moving in response to sound. There are no other mics plugged in.

In Garage Band > Preferences > Audio/MIDI > Input Device set to Blue Snowball and then record and no sound is recorded and the level meter doesn't show any audio input. When I switch to Built In as the source I also get nothing. 

I tried plugging the mic into each of the two USB ports with no change.

I also opened the Audio MIDI Setup App and tried turning the volume for the Blue Snowball all the way down and back up which I saw as a recommendation somewhere.

I downloaded Audacity (2.3.0) and it is able to record fine from either the Snowball or the internal mic.

GarageBand 10.3.1

macOS 10.14.1

MacBook Pro (Retina, 15-inch, Early 2013)

The Blue mic works fine on a MBP 13" Late 2013 running the same version of macOS and GarageBand.
Some solutions found here:

Have you set the mic as the input in GarageBand? (make sure the mic is
plugged in, open GarageBand, click on the GarageBand menu, Chose
Preferences, Click on the Audio/MIDI from the preferences window tool
bar. There will be a pulldown menu called &quot;Audio Input,&quot; click on that
menu, and select the Blue Yeti. )
If your still not getting any audio in from the Yeti, have you tried
setting the Yeti as the audio in in system preferences? if so, do you
get any activity Level Input bar while it's selected? if not, is input
volume set to 100%? (far right end of slide)
Have you tried resetting the cable on the mic side?

If none of this works you might have to send it back as deffective.