There's a couple of possibilities: First, that member somehow got left behind in the old ward. In that case, the new ward should be able to request the record. The other is that their record was never in the system. Perhaps as a non-member spouse and it's only noticed now because for some reason the directory isn't displaying that. Third, they might have opted to attend a singles ward rather than follow the family.
Either way, I think I'd call support and see what they see from their end. Having spent far too much time fixing computer problems, I'm always weary that an unusual problem is just the tip of the proverbial iceberg. There's always the possibility that more people are affected and just haven't been detected (yet).
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