Your Line 6 audio interface sends/receives the signal to your recording software through it's ASIO device driver. However, your device has more than one input, so the ASIO driver needs to know which input to monitor for the signal. Right now (since recording through the guitar input jack is working), the driver is set to monitor signal coming from the "Instrument" source (the guitar jack). You need to tell the driver to monitor signal coming from the "Mic 1" source (the XLR microphone 1 jack). You can accomplish this a couple different ways:

1. In POD Farm, go to the Mixer View and just below and to the left of the Line 6 logo, click on the dropdown menu that currently reads "INPUT: Instrument" and change it to "Mic 1"
2. Or, if using GearBox instead of POD Farm, click just below "SOURCE SELECT" on the left hand side and select "Mic 1" instead of "Instrument".

Now the ASIO driver will pass the signal coming from your Mic 1 input to your recording software. Also note that your UX2 device is capable of recording two channels at a time. So with the right input source selections, you can record with 2 micrphones, or a microphone and your guitar, or even the line inputs on the back of your UX2.