Writer mail merge using spreadsheet as source

I have created a document w/ fields from a spreadsheet, both in native ODF.
One of the columns in my spreadsheet is a case number, which is all numeric.
When I run the mail merge, the data in the case number column is not written
to the document. The rest of the data, all text, is though. Is this a bug or
a formatting issue? Thanks!

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Jeff Prater