I tried to get this working where the SkelMesh was nested in the pawn’s MotionController componenrt (for Oculus Rift Touch) component. This would seem logical because then the mesh just follows the controller around directly. But from there the cast to anim instance always fails.
Instead, I made the Skelmesh in a new actor and made this actor a Child Actor directly under the pawn’s scene root, and Attached the child actor to the motioncontroller component at beginplay. Now I can directly cast into the skeletal mesh’s anim instance just fine.
This problem seems a bad limitation and I don’t understand it really; I’m just glad I found a work around.