I've figured out what the problem was; figured I would post the answer here in case anyone else runs into the same issue in the future.
The problem was that Direct2Drive has not distributed the most recent patch for the game. D2D only patches it up to version 1.17.5; this version apparently has some serious scripting bugs in it that, among other things, prevent the "hill 243 captured" event from firing. BestWay have a patch that fixes these (1.17.5
.1), but D2D doesn't distribute it, so if you rely on them for your patches you end up with a broken game.
The solution is to
download patch 1.17.5.1 from the 1C website and apply it to the game; this fixes the scripting issues. The patch works fine on the D2D version even though it doesn't come from D2D.