When editing a Banner section, changing the Font sytle in Heading works, while changing the Text Style for the Heading in the inspector has no effect.
Altering the Font Style and the Text Style for the text does work.
Tried to reproduce this issue. I changed the Family and Style and it all seemed to work just fine.
What am I missing? 
That’s odd. I had saved the project and now just re-opened it and the Heading is working.
I’ll let you know if it happens to me again; it definitely wasn’t working. 