Line disappeared once the perpendicular constraints applied. (Mstn v8i SS3)

I have an issue, that cannot resolve myself.

Situation: DD Design.

Apply perpendicular constraints Line to Line - all OK; both lines and constraints symbol are visible.

Apply perpendicular constraints Line to Ellipse - line disappeared from the view; ellipse is visible, constraints symbol is visible.

If use "Modify and Resolve Constraints" tool, the ellipse is ON, line WAS invisible (anyway), and the constraints symbol is also disappeared.

Where I should look, to resolve strange behaviour.

Thanks.