Mariano aks Why are my SmartLists not formatted when exported to Excel?.
The Dynamics GP Blogster: GP 2013: Why are my SmartLists not formatted when exported to Excel?
Reporting & BIExcel & OfficeMicrosoft & the GP EcosystemGP 2013
Archived post from 2013. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.