A case of alleged supernatural messages in Amsterdam in the 1950s reportedly had our Lady presenting herself to the faithful under the title of “the Lady of all Nations” and asking the Pope to make a declaration of dogma about her as Co-redemptrix, Mediatrix, and Advocate. These titles are already well established in Catholic thought, and have an interesting application to the role of the Church as a means of grace and salvation, but with so many cases of false mysticism about, one has to be careful about signing on to some particular movement’s proposals for the Church.
This May, the CDF (the Vatican’s doctrinal office) has given a warning about one aspect of that “Lady of All Nations” devotion: a prayer associated with the messages, and found on Catholic sites such as EWTN’s, raises the CDF’s caution and is not to be used.
Abp. Angelo Amato, SDB, the secretary of the Congregation for the Doctrine of the Faith, wrote on May 20:

With regard to the devotion known as ‘Lady of All Nations’ and the Marian apparitions experienced by the late visionary Ida Peerdeman, I wish to advise Your Excellency that although the said apparitions have received approval from His Excellency the Most Rev. Joseph Maria Punt, Bishop of Haarlem (Holland), in his Communications of 31 May 2002, the Congregation for the Doctrine of the Faith has expressed concern regarding one particular aspect of that devotion whereby official prayers invoke the Blessed Virgin as Lady of All Nations ‘who was once Mary’…..[The CDF] does not permit any Catholic community of Christ’s Faithful to pray to the Mother of God under the title of ‘Lady of All Nations’ with the added expression ‘who was once Mary’.

(Thanks to Mark Waterinckx for the tip.)