Before spending more hours configuring the Fixer Upfront child theme, I setup a menu item link to a page with a bbPress 'Forums List' widget. The formatting of what the widget rendered with Fixer is completely different contents compared to the TwentyFourteen child theme. Also, clicking on a Topic in the Fixer theme only yields the topic title, but no article and no comments/replies for that article. Switching the theme back to the TwentyFourteen child theme and refreshing the same URL on a different browser window yields correct topic content.
At this point I am giving up on using Upfront. The incompatibility with bbPress combined with no live preview adds up to a showstopper for me.