Thanks for all the helpful suggestions. My problem is now fixed. I'm not quite sure how I fixed it, but I'll describe what I did in case it helps someone in the future.
When I first installed the servos (servo #1 in pitch position and servo #2 in roll position), the system recognized servo #1 as needing a firmware update but it didn't see servo #2 at all. After updating #1, it still didn't see #2 and that's the situation I was in when I last posted.
Today, I checked the continuity of all the wiring between the roll servo and the panel, and all of the connections were indeed correct. [As an aside, the network wires (twisted pairs) are all connected in parallel as a couple of people mentioned above, but the two servos are wired independently to the Control Module, so it is in fact conceivable that an error in the harness could affect one servo and not the other.]
Anyway, I pulled servo #2 from the roll position, thinking that there was something wrong with that motor (since I found nothing wrong with the wiring). I then connected servo #2 to the harness in the pitch position just to confirm that it was defective. I didn't expect it to work, but when I powered the system up, the Skyview recognized servo #2, and indicated that it needed a firmware update. After updating it, I put servo #2 back in the roll position and reconnected #1 at the pitch position.
At that point, everything worked fine and the system recognized both servos on the network.
Strange, but I'm glad it worked, and hopefully this might help someone who finds themselves in the same situation.