First, check to make sure that the email address is not already associated with a different record (Search for the email address on Constituent360). If the email is already associated with another record and you are wanting to add the same email to your current constituent, reach out to Luminate Support. 

After you check and verify that the email address doesn't exist in the system and isn't associated with another constituent record then reach out to Mike Cutlip at Mike and his team can review to make sure that NRDS information is syncing to Luminate Online.

The sync between NRDS and Luminate Online may not be running routinely due to various reason.