It seemed the other way around, locomotion was using LateUpdate, and changing it to use Update worked - thanks for that. What implications are there for changing locomotion to use Update that I should watch out for?
Thanks Justin, I got it working. Now I'm just noticing camera jitter on the object being ridden. I can provide a video if needed, but the only search result here on the forums I found that seemed related was a topic from 2020 here.
I also have this issue. I have a vehicle controller for boats/rafts that uses the physics and rigidbody engine (non kinematic) and I can't find any way to make the character controller stick on top of it once it lands there. Implementing a 'driving' controller seems really backwards.