So flipping useful… thank you!
You are right about the bug… it should be Player Rotation (Pitch and Yaw with Roll zeroed)… though this of course won’t fix it. As you know, my issue was a basic misunderstanding of how Rinterp works.
With the understanding you’ve given me, I’m going to use Select Rotator to switch between Full Player Rotation and Zero Roll Player Rotation in the Rinterp Target. Right now I’m figuring out the best way to trigger this switch. Will post my progress in a day or two 