OK, after getting the runaround I have a few observations.
(1) It is not helpful for TCH support to send us mere customers off to IPB official forum at http://forums.invisionpower.com because it is not a support forum.
I found a handful of topics asking for support and a few halfhearted attempts to give it, but the rules clearly state that it is not a support resource. To get support you must use a different forum at http://www.ipsbeyond.com/forums/ or log in and submit a ticket at https://www.invisionpower.com/customer/. Both of these require a user account which you don't have unless you are a direct Invision customer. Using their products through an account here at TCH does not constitute making you a customer, so you are locked out. I attempted to post my problem at http://forums.invisionpower.com anyway and got slightly tongue-lashed for it.
(2) Despite my tongue-lashing, the guy who shut me off at http://forums.invisionpower.com did suggest I visit http://forums.invisionize.com, which is not directly run by Invision. It was VERY helpful, and I would suggest that TCH keep this resource handy for anyone with future IPB problems of any type.
(3) The problem was actually more complicated than the solution that nortk ran across. In the end I needed to modify four files (none of which ended up being sources/functions.php lol). Still I award him a medal for actually attempting to help me. Thank you!! I now feel like an all-powerful code god, as I have made changes and the problems have been vanquished.
In closing, should anyone else have this problem and run into this thread through a search, the specific fix can be found here:
http://forums.invisionize.com/index.php?showtopic=73882
Cheers.