It just occurred to me to try manually appending the twig collection from geo_nodes_2_93.blend into my new Blender file before I ran Add Leaves, and with that everything processed without issue.
Hurr durr, right?
One other thing I’ve noticed is that the tree mesh is created with flipped normals. IDK if there’s a reason for this, but I just make sure to either flip them or recalc outside, and then all is good.