My DDs working memory was also tested by the audiologist who confirmed her auditory processing disorder. Her working memory was on the 13th percentile on her wisc scores. In the audiology testing she had two auditory working memory tests under 2% (this was what earned the diagnosis) and one at 98%. she failed the tests using meaningless data and aced the ones with meaningful data.
Which in a classroom translates to little or no chance she will be able to retain completely new terms, concepts etc delivered orally but may do very well on expanding existing knowledge. Which explains why her teachers can never predicted when she will have no clue what they were talking about or understand something everyone else missed.
I feel like the audiologist's working memory tests were more useful than the wisc tests. The addition of a meaningful data test gave a much more complete picture.