OK, we figured out what was causing the problem. Left arm moved the vehicle, and I was using world space to alight the character to the vehicle. Seems the evaluation of the world space of the socket on the vehicle was a frame behind, so the left arm moved the vehicle after it got the position of the sockets and updated the character’s anim graph.
For now we’ve set everything to component space. Since they’re in the same blueprint that’s working for now, but is there a better solution for getting this to line up better?