What I am aware of are places where Masoretic text differs from other sources, which some scholars (many Christians) believe are better. The Masoretic text was one that was traditionally used by many Hebrew translations. And, while I don’t know the specifics offhand, I do remember many situations where footnotes would give an alternate reading based on the Masoretic text.
I’m also, of course, aware of the verses that Christians consider Messianic and to refer to Jesus, where, of course, Judaism disagrees. But I cannot think offhand of Scriptures that come from the same source but which are translated differently, let alone ones where Christian scholars say that something is unknown while Jewish scholars say otherwise.
One thing that I think they might be referring to be referring to is some situations where the Oral Torah or Talmud explain the underlying meaning of an ambiguous verse. Christians tend to ignore these when interpreting things, so they might retain the ambiguity where a Jewish person wouldn’t. Then it wouldn’t be so much a translation issue, but one of interpretation.
However, I don’t know if such a situation exists, as I am not very familiar with those Jewish sources.