Thanks very much Dave. That was my backup plan, which I ended up using.
Would be nice to know if there’s a way around this for the future, though … I can imagine more complex situations where going old school might not be feasible, with more objects in the matte layer, strange shapes on crazy paths, etc. (e.g. keyframing this was a little bit of a pain with getting the speed ramps just right, and it was a very simple movement.)
Anyone know?