@todd @ivory Okay, I've disabled Reduce Motion, and the issue still occurs, so it's not related to that after all, sowwy.
But it might be even more specific than that: it's when navigating back with the ← arrow key, then attempting to scroll *while the mouse cursor is on top of the Ivory window*.
The view will not scroll until I move the mouse outside of the Ivory window, then back over the window (without clicking).
Here's my attempt at recording it (keep in mind that I'm scrolling my mouse wheel after I've hit the ← arrow key):
