I think we all have been mistaken:
In "The Court of the Last Tsar. Pomp, Power and Pageantry in the Reign of Nicholas II" Greg King describes the presentation of debutantes (pages 309-310). It was a regular ceremony taking place at the Winter Palace each January with both the Emperor and Empress present. For the first few years of her reign, Alexandra Fyodorovna continued the tradition. But because of her ill health and dislike of such great court ceremonies, she abandoned the traditonal form and started inviting two to three young women at a time (with their mothers / chaperones) to small receptions held several times a week at one of the imperial palaces. But, as Baroness Buxhoeveden, who herself was presented at one such reception, recalled, it did not help that much against the Empress's severe anxiety. Buxhoeveden's mother had to, against all court etiquette, start the conservation, because the empress was silent for such a long time after they sat down. But she eventually livened up and Buxhoeveden thought she made a warm impression, whereas the daughter of the French ambassador recalled her presentation as one of awkward horror because of the Empress appearing so ill at ease.
Greg King further relates (page 460) that there were specific imperial bals blancs for debutantes, who appeared in white gowns and were watched by chaperones. The only dances at such a ball were cotillons, quadrilles and waltzes, all lively dances were banned. There was no orchestra, just simple piano accompagnement. During the cotillon, carts of lavish flowers from the Riviera were wheeled into the room. No enlisted man or students of the elite schools were invited to the balls, with the exception of the senior class of the Corps des Pages. At midnight, the young dancers sat down at round tables to dine on smoked salmon and sturgeon, caviar and all kinds of fruit.
