Test Whisperer?

The situation is so weird that at this point we are still more amused/puzzled than worried – but the clock is ticking…
The kid had all perfect scores in the brutal selective enrollment process, went to the highest-ranked HS in the city, that recently has reached dizzying heights in various nation-wide rankings.
Now junior, straight A student, all As on her 3 APs so far, complemented by all the teachers - even the math teacher, although the kid is passionate about music and languages, not math.
But the trial tests, both ACT and SAT, even after quite a bit of prep (which the kid insisted was very helpful) are abysmal, in the 1310/28 range.
The kid says “I can’t get into their way of thinking,” and becomes visibly tense at any mentioning of these tests, while school tests are no problem at all - almost uniformly in the 96-100% range.
Considering all other data points, this seems just bizarre, and neither the kid, nor we have any idea how to get out of this hole - we doubt whether more of a typical test prep will change much. We are actively researching test-optional schools but the choices are still limiting, and the ECs, while impressive, are not off-the-charts so just giving up on the tests strikes us as risky.
Any suggestions/similar experience?

We used a private tutor. Came to our home, tailored the tutoring to exactly what our daughter needed. Worth every penny.

Tests are all so different. What makes you think the test for entrance is the same as the SAT? Seems unlikely unless it was made by the College Board, like the SSAT. IF she took the SSAT and aced it and now is having trouble with the SAT, I can see why you are confused.

Some kids are intuitive and can guess and eliminate. These kids do well. Others are perfectionists and over read the questions. ( I have one kid of each both are in the top 90’s on scores but they approach it differently). Actually the more intuitive one is usually 98/99% and the other 95%

Tutoring is great for some kids, might make other kids really nervous.
My sophomore recently took the PSAT and the biggest issue was timing and missed a small section. I think being comfortable with the test is a big plus. But also remember studying to learn something and master it, is very different from taking an SAT which really reviews things one learned long ago and asks students to think in multi-dimensional ways( analytical, facts, etc).
Being good in school and being good on the SAT are two very different beasts. IMO, standardized testing skills are pretty innate and can be improved with practice.

We found tutoring helpful for “test think” although D had little need of “substantive” tutoring. Might help with the stress yours is apparently feeling. Also, test optional appears to be more and more of a thing.

@Happytimes2001 SSAT was not required. But the kid took ISEE to a great private school s/he is not attending, MAP, and Selective Enrollment Test administered by the public school district, and aced them all. The kid remains an enthusiastic student in a school full of extremely bright kids - with no issues, really, other than these damn standardized tests. That’s the reason for our confusion - the results are just outside the normal distribution, by a lot, I’d say.
Thank you guys for all your suggestions, looking forward to more of them

I would guess that the ISEE and other tests are just different. My kids tend to test really highly on SAT/SSAT but test about 5% lower on the standardized grade tests.
I wouldn’t worry about it. I’m sure you can work out a plan that makes sense for her. And yes, that sound like it’s off by a lot compared to her old scores.