Background: Hattie McDaniel (June 10, 1895 - October 26, 1952) was an American stage actress, professional singer-songwriter, and comedian. She is best known for her role as "Mammy" in Gone with the Wind (1939), for which she won the Academy Award for Best Supporting Actress, the first Academy Award won by an African American entertainer. In addition to acting in many films, McDaniel was a radio performer and television star; she was the first black woman to sing on radio in the United States. She appeared in over 300 films, although she received screen credits for only 80 or so.
Context: The whereabouts of McDaniel's Oscar are currently unknown. In 1992, Jet magazine reported that Howard University could not find it and alleged that it had disappeared during protests in the 1960s. In 1998, Howard University stated that it could find no written record of the Oscar having arrived at Howard. In 2007, an article in the Huffington Post repeated rumors that the Oscar had been cast into the Potomac River by angry civil rights protesters in the 1960s. The assertion reappeared in the Huffington Post under the same byline in 2009. In 2010, Mo'Nique, the winner of the Academy Award for Best Supporting Actress, wearing a blue dress and gardenias in her hair, as McDaniel had at the ceremony in 1940, in her acceptance speech thanked McDaniel "for enduring all that she had to so that I would not have to". Her speech revived interest in the whereabouts of McDaniel's plaque. In 2011, J. Freedom duLac reported in the Washington Post that the plaque had disappeared in the 1960s. In November 2011, W. B. Carter, of the George Washington University Law School, published the results of her year-and-a-half-long investigation into the Oscar's fate. Carter rejected claims that students had stolen the Oscar (and thrown it in the Potomac River) as wild speculation or fabrication that traded on long-perpetuated stereotypes of blacks. She questioned the sourcing of the Huffington Post stories. Instead, she argued that the Oscar was likely returned to Howard University's Channing Pollack Theater Collection between the spring of 1971 and the summer of 1973 or had possibly been boxed and stored in the drama department at that time. The reason for its removal, she argued, was not civil rights unrest but rather efforts to make room for a new generation of black performers. If neither the Oscar nor any paper trail of its ultimate destiny can be found at Howard today, she suggested, inadequate storage or record-keeping in a time of financial constraints and national turbulence may be blamed. She also suggested that a new generation of caretakers may have failed to realize the historic significance of the 5 1/2" x 6" plaque.
Question: If it was returned, why can't it be found?

Answer:
she suggested, inadequate storage or record-keeping in a time of financial constraints and national turbulence may be blamed.