Here we have a minor error with the negative word not. The 1841 British edition omitted the not in the notwithstanding-clause, an obvious typo that the subsequent LDS edition (1849) corrected by restoring the not. Perhaps the 1841 typesetter was not expecting a not within a notwithstanding- clause. Elsewhere the text generally avoids negatives within notwithstanding-clauses, the only other example being “notwithstanding they were so numerous that they could not be numbered” (Alma 2:35). Yet even in that example, the main clause itself is positive (“they were so numerous”).
Summary: In accord with the reading in 𝓟 and the 1830 edition, maintain in 3 Nephi 7:11 the use of not in the notwithstanding- clause.