I’m Jewish, but have been part of the official Christian-Jewish dialogue (especially with the Roman Catholic Church) for over a decade.
While it has been a popular belief of the past that the Masoretes, the scribal scholars who preserved and codified the Jewish Bible between the 6th and 10th centuries CE/AD, changed the Scripture text to disfavor readings that support Jesus as the Messiah, the discovery of the Dead Sea Scrolls of Qumran proved that wrong.
The reason for that popular belief was that Jews in general tend to disfavor the Septuagint while Christians favor it. Arguments and teachings such as “the Jews changed the Bibles in the Masoretic text in their hatred and rejection of Jesus” was one of those arguments that fomented the flames of Holocaust propaganda. With both the end of the Nazi regime and the discovery of the Dead Sea Scrolls, Christianity had reason to look back at its own history, especially since the Shoah arose in Christendom’s very own backyard.
The Catholic Church took the very first steps of opening official dialogue with Judaism after the Shoah (the Holocaust). Along with that, the Church took to the front of the line in the field of critical studies, developing new guidelines for the production of Bible translations for the faithful. The discovery of the scrolls at Qumran were 1000 years older than anything the Church had on hand and more than 100 years older than the time of Christ. They favored the Masoretic readings, and where they differed, they differed mostly in spelling.
After that, the discovery of more ancient texts far older than the Septuagint proved the same, favoring the Masoretic tradition. Therefore scholars, including the Church as a whole, declared the Masoretic texts as the standard.
In some instances, however, the Septuagint reading is to be followed and accepted over the Masoretic reading for Catholics because the Septuagint reading was the one originally canonized. However, the Church has remained firm on scholarly and academic readings, generally embracing Septuagint readings for liturgical differences only, but noting the Masoretic text as the original for study.
As of late, some liturgical readings that don’t affect Church teaching have been adjusted to read according to follow the Masoretic text as far as the vernacular of languages might allow. As far as I know this has not happened in English in any major areas.