Been on the receiving end of that
My middle daughter's 'A' level music course was full of brilliant musicians playing for County Youth Orchestras, Brass Bands, etc and most received 'A' and 'A*' in their academic subjects.
When the whole course gets a 'U' grade and the school will not request a re-mark, you know that their work has not been submitted and there has been a cover-up by the school! The Head of Music did not return in the Autumn!
Some of the children were permanently affected by the teachers lack of IT skills and inability to follow backup rules - the perceived problem. Luckily my daughter still had enough grades to get into her second choice university where she easily gained a First last year and was star of the Brass Band in the city. But the 'U' grade in 'A' level music will always live with her.