I have no trouble recording (and playing back) a single track, but when trying to add a second track, I only hear 2 clicks, and nothing is recorded.
What makes this most baffling is the fact that I had no troubles 6 months ago. I believe I still have everything configured the same (but with Windows, who knows).
Windows 10, Audacity 2.1.2
Interface is Behringer UMC204HD
Update: I was trying to use the Behringer for both input and output so I could hear my guitar and recorded tracks in the headphones. If I change the output to the speakers, the recording works (yay!). Unfortunately, I have to set levels such that I hear the guitar in the headphones and the recorded tracks over the speakers.
I don’t remember this being the configuration 6 months ago, but I guess it was.