This can occur because the Hon/Mem > Description field is looking for the donor's Honor/Memorial Description (found on the Tribute tab of the donor's record. 

To export the receipted gift's Honor/Memorial Description, include the Description field from the Gifts category.

1. In Mail - Receipts, select the Fields to Export tab
2. In the Available Fields, open the Gifts folder
3. Move Description in the gifts folder to the Fields to Export frame

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