correct grade for her age
While I understand you mean that she is not grade accelerated, there is really no such thing as "correct grade for her age", and buying into that myth can be damaging to one's own gifted kiddos and to the gifted community at large.
The concept of "correct grade" for one's age highlights the difference between the positive principle of "matching the program to the child" and the common practice of "matching children to a program" (which can result in an ill fit and/or children falling through the cracks). The book
Re-forming Gifted Education and the related Gifted Education Planners help parents/teachers/advocates with "matching the program to the child."
Based on the information provided, especially that your child would rather read a book (from which she is presumably receiving the mental stimulation of learning something new) I would tend to say that her school refusal is legitimate, and based on boredom... therefore her curriculum and programming need to change.
When you look at the homework assignments which she has skipped, do you find they are just "busy work" for her? Are they challenging? Or just time-consuming?
On the other hand, being "stubborn" may be related to "inflexible thinking", a possible sign of some 2e issues. A simple check for EF issues may be to observe her level of planning and follow-through at home. Does she have an assignment notebook or planner? Are homework due dates written in it? Do you discuss with her the amount of time she thinks each will take? Are her estimates fairly accurate? Is she aware of the passage of time and able to get herself ready for scheduled activities and events? Is she able to break larger assignments into smaller sub-tasks and state the order in which they need to be accomplished?
Is the counselor she is seeing familiar with giftedness and 2e? Or when speaking with the counselor, might your DD10 be compensating with her giftedness so that 2e issues are not detected (but rather attributed to negative "personality" characteristics)?
