Project World Location to Widget Position not precise

Hey, I’m trying to display an icon on the corner of a wall, but the widget position loses precision with the camera’s rotation.

This is the correct position (when I look directly at the edge):

These are incorrect (when I slightly turn left/right):

I am using the ‘Project World Location to Widget Position’ function to get the screen position. The red debug sphere is drawn at the location I’m passing to the function, and, as you can see, it remains the same (I’ve double checked it - the world location does NOT change at any point).