They identified 10 specific related SNPs on the X chromosome as part of a side study. The study itself was of 1271 sites. That number is right there in the first sentence of the abstract! And the summary sentence is awfully clear: "A joint (multi-phenotype) analysis of educational attainment and three related cognitive phenotypes generates polygenic scores that explain 11–13% of the variance in educational attainment and 7–10% of the variance in cognitive performance".

Who's being misleading here? That "generally accepted range" you're trying to invoke is precisely was is being studied here. And it was wrong, largely because the people generally accepting it were confusing social factors with genetic ones.