I activated a licence with new model (Creator, Explorer and Viewer) in the 10.4 of Tableau Server but Tableau won't recognize the Seat of that licences.
What you're seeing is accurate. The newer Role based model started with version 2018.1.x so Tableau Server would need to be upgraded to that version before it can "unlock" the newer role.
Become a Viz Whiz on the Forums!
Support the Community and master Tableau.
Retrieving data ...