Apple's new OS Mojave 10.14, has implemented a new security feature that can block input signals if not allowed access. Once a user has launched a DAW or stand alone plugin for the first time after the Mojave update, they will prompted to "allow mic access." If mic access is denied, user will not be able to receive an input via the specified software. To manually approve your software navigate to:
System Preferences > Security and Privacy > Privacy > Microphone
From this menu, user will be granted the ability to approve any software that was previously denied.