Thanks!
Thanks to all for the replies. As I started trying to find the bad junction, relocating the switch levers, checking the joint connections, the errors just kept compounding. As I went through one section of track, I started getting more errors in the next section, some giving me the "after junction xxx" message, some not. Went through that section of track and the next section started showing errors.
I finally wound up just rebooting the PC, and the problem instantly cleared up. I'm assuming there must have been some kind of glitch loading the route or session.