Here in the printer’s manuscript, Oliver Cowdery initially omitted the subordinate conjunction that after it came to pass. Later he supplied the that, but in the wrong place (after the preposition in rather than before it); the level of ink for the supralinear correction is heavier, so Oliver’s correction probably occurred when he proofed 𝓟 against 𝓞. The 1830 edition has the that (and in the right place), so undoubtedly 𝓞 did too. For another example of the loss of that after the phrase “come to pass”, see nearby under 3 Nephi 4:1.
Summary: Maintain in 3 Nephi 4:5 the subordinate conjunction that after it came to pass, the reading in the 1830 edition and the implied reading in 𝓟 (where that is supralinearly inserted in the wrong place).