Why sometimes the Z-axis coordinate is missing?

While hovering on the majority of objects that are on Z-axis 0 is displayed properly by the mouse tooltip (like 0.0000000), I noticed that sometimes the Z-axis coordinate is missing from the mouse tooltip, despite the fact that they are also exactly on the CPlane. Is that a bug in Rhino, or some hidden feature that I can’t understand? :slight_smile:
Check the video below. It’s funny that when I copy the same object along the Y-axis or X-axis, the Z-axis coordinate is displayed inside the mouse tooltip, but not on the original object.

Missing Z-axis coordinate.3dm (101.3 KB)