If the acquisition was tilted you may need to rotate to volume plane (click the “pushpin” icon in the top-left corner of the slice view, then click the double-arrow button on the left, then the “Rotate to volume plane” icon appears):
Here’s an example drawing on the original slice (patient space)
And here the paint stroke on the right is after rotating the red slice into the acquisition plane and only one plane is painted in the other views.
