Confirm that soft credit information exists on the gift records:

1. In Records, click Gifts, and open the gift that is missing the soft credit information
2. Select the Soft Credits tab
3. Enter the soft credit information.
4. Repeat for each gift missing the soft credit information in the export.

OR

If the export is using a query (with the Include button on the General tab), ensure that the query is set to credit soft credit recipients