Disappearing Input Source on GarageBand

I recently purchased an Art Studio Dual Input pre amp to run through a USB to connect to Garage Band for demo recording. I have an AKG studio mic that I have always run through the right input source. When using this to record in Garage Band, it always gave me a "Mono 2 (USB Audio Codec)" and "Mono 1 (USB Audio Codec) as options in the input source drop down box. I always used Mono 2 obviously as it corresponded with the right input source on the pre amp. I opened up Garage Band about a week ago, and the Mono 2 input source randomly disappeared. I am not able to find it as an option anywhere now, and when I tried to move the mic to the left input and chose Mono 1 as the input source, the recording comes through very staticky. When I have my headphones in and speak into the mic while it is plugged into the right input, I can hear myself. However, it is not translating through from the mic, through the preamp, and to Garageband under Mono 1 (which I am assuming is because it needs to be under Mono 2). Has anyone ever ran into this problem before? Any tips on how to get Mono 2 to show back up in GB?