Defective grants recorded before April 27, 1994

(a) Any instrument recorded in the Office of the Recorder of Deeds before April 27, 1994, shall be effective notwithstanding the existence of 1 or more of the failures in the formal requisites listed in § 42-404, unless the failure was challenged in a judicial proceeding commenced within 6 months from April 27, 1994. (b) Nothing in this section shall affect the validity of instruments recorded before April 27, 1994, which have been validated by prior law.