Hey, Kruno.
Thanks for the ideas on how to solve this.
Yesterday when I clicked the Fusion page I saw an empty comp, just media in / media out, nothing to do with the Fusion effect I'd created. Not surprising that there were also no keyframes, I suppose.
I tried what you said, and this time it opened Fusion with the effect nodes as I would expect, and the keyframes were also there. So then I closed and reopened the project, tried doing everything I did yesterday and could not reproduce the original problem. No matter what I did, Fusion always opened with all the nodes and keyframes.
I guess somehow it got wrapped around the axle, and today everything's happy. I'm just going to take the win.

Appreciate the help on this, man.