I had enough stuff in one place to set up for an overdubbing session with the Behringer UM2 Preamp. That’s a yes. It works perfectly. That’s the good news.
I’m using Audacity 2.1.2 in OS-X 10.9.5, Not Yosemite.
I made it through two intact tracks, one rhythm and one melody. It’s insanely difficult to do this in passes when you’re accustomed to playing the whole song yourself all at once.
I fluffed one phrase on track two and since the song has multiple repeating phrases, I copied a good one with the idea of starting a third track, pasting the correction, slipping it into place, muting the broken fragment and Bob’s your uncle.
Didn’t work.
I created a new mono track (they’re all mono) pasted the short correction and all the other tracks shortened themselves to the length of the correction. Doesn’t matter how many times I select the new track or what I highlight. I can’t get the old tracks to ignore what I’m doing on the new third one.
I selected the Time Shift Tool and all the tracks shifted.
My guess: You have inadvertently enabled “Sync Lock”, but I don’t know why you have not reported “clock” images on tracks.
Could you give a click by click account starting with how you did that: “With the first track selected and highlighted, I clicked 'Tracks > Add New > Mono Track”
That’s not good news. You were supposed to say, “Oh it sounds like you have the frammis preference set wrong.”
Audacity 2.1.2 is not used for production on this machine, so for all practical purposes, it’s right out of the tin. It’s scary this seems to be default behavior.
I may finish the test on another machine just to get it out the door (original goal) and then get back to this.