ok… I think I figured out the issue…
The Inverse Transform Rotation BP node works just fine, it was the way I was using it was causing some kind of feedback/feedforward jittering: kind of calculating it and then resetting it simultaneously (I’m not sure what this is called)
To get around it, I put a scene component in the same location and used it’s transform and rotation instead. It seems to be perfect… but if someone who is more skilled than me would please confirm I’m right, it would be a relief 
