Well, I went through widget panel and tried to add Sufflehound Advertise in header section but options/contents within any of Sufflehound widgets are not visible. Due to which I am not able to make changes to widgets and also add an advertisement to both header and sidebar.
I hope you are well today and thank you for your question.
I could confirm the issue on my test site therefore notified the theme developer about this so that it will be fixed.
The issue will be fixed ASAP.
In the meanwhile you can use the widget from Admin Area -> Appearance -> Widgets as shown in the attached screenshot.