Well, I’m happy to say that after much searching on the net I’ve solved this. In the event someone else should have this problem, I am letting you know my solution. It turns out that the video asset in question had a space at the front of the timeline (likely at the time marker 1.6016s). I dragged file to the beginning of the timeline, eliminating the space, and the dvd was built!
I did find another interesting solution for others with encoding issues, which is to select the asset in question and choose File>Revert to Original. Then build the dvd and let Encore re-encode.
I hope someone else finds this info useful and doesn’t have to troubleshoot for days like I did. Now I need to post another question re: forced letterboxing…please look for it if you’ve got answers!