Yep! Yep! Yep! I'm sure many people look at my DD9 and don't believe she is gifted. (heck, DH and I wonder sometimes ourselves) She isn't a highly driven and self-motivated giftie. She is impulsive, sometimes immature, won't listen, and doesn't like to "shine". She has gone from curious and questioning everything to oh well, no big deal apathy. She would rather play Minecraft, watch cartoons, and be outdoors, than be researching something new that made her think.

KnittingMama's son sounds very, very similar to my kiddo. I also suspect public school and the constant repetition of basic work and not being challenged is partly to blame.

I totally agree with what others have already said and suggest -
1. check out info about underachievement and perfectionism
2. find something your DD really loves and watch and see if you see the "spark"
3. try giving her some higher level little things to try and see if she gets it - also pay attention if she says I can't do this because it is too hard, even if you know she can
4. talk to her about it - they can really fill you in sometimes if you just ask
5. do some after-schooling and see where it takes her
6. talk to someone at school that might have some ideas - one of the tests you mentioned was from the school, so what is school doing to help your DD

Good Luck!!!