Tutors cannot make edits to a Lesson Report once the Invoice or Payment Order has been raised for the associated Lesson.
An Administrator will first have to void any Credit Request, Invoice and Payment Order associated with the Lesson before edits can be made to the Lesson Report. You can find these via Activity > Calendar > select the Lesson > Accounting.
Once those are voided, the Lesson Report can be edited via Activity > Reports > select the Report.