[ODE] Trimesh collision doesn't seem to be functioning in my case

[Ryan O'Connor]

I tried compiling ode UNSTABLE and using it on an existing project. I hoped
it would improve stability of collisions. At the moment if the frame rate of
our game drops below about 40fps, or you go too fast into a wall
(sphere-trimesh collision), the sphere will penetrate straight through. What
I found was that no collisions are detected between the sphere and anything.
All objects are in the same space and I have custom collision code on the
callback to quickly discard irrelevant objects from collision response. It
all worked ok on 0.5 stable, but not on the latest unstable branch. Any
ideas? What has changed that's relevant since then? I'm kinda stumped.. It
leads me to believe I set my basic scene up wrong before and it's only
evident now because the ode code is better.