Agree with several PPs:
--I'd see EF difficulties and very serious anxiety/perfectionism as likely root causes
--I might consider medicating for the anxiety (if she will agree to that); it's clearly causing real suffering. I would use a psychiatrist or developmental pediatrician to select a medication rather than a primary care doc.

When our DS lied about assignments, it was because the fear of being in trouble was worse than the fear of the zero. We needed to ramp the anxiety way down, then deal with the EF failures. (The EF failures were a combination of perfectionism and true disorganization. Some support at school and some maturity and some ADHD meds helped greatly.)