The GP Support team helps with No Data Returned When Using a JOIN in SmartList Designer
No Data Returned When Using a JOIN in SmartList Designer – Dynamics GP Support and Services Blog – Microsoft Dynamics GP – Microsoft Dynamics Community
Microsoft & the GP EcosystemReporting & BI
Archived post from 2014. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.