Hi George,
Thank you for contacting Syncfusion support.
In our standard SkinManager Themes, we have provided style only for the ApplicationMenu in Blend style. Therefore, BackStageHeader is not visible in classic themes. In our SfSkinManager themes, we have included the support for BackStage in Blend style. So, we suggest you use the SfSkinManager themes to make the BackStageHeader visible in your application. We have prepared a simple sample in Ribbon with SfSkinManager theme and it can be downloaded from the below location.
Regards,
Keerthana J