I don't see any evidence that suggests the test is invalid, but that doesn't mean the results are necessarily indicative of her true ability. I think what you may be looking at is a 2e situation, where some of her gifted-type traits are being masked by her (I'm guessing) executive dysfunction-type traits, whether the latter is ADHD, disinhibition, or possibly another dx, like NVLD or ASD. (Obviously, I can't diagnose her over the internet. ) And vice versa.

...pronounced like the long vowel and first letter of the alphabet...