This one is for B2 developers. All of our current supported Learn builds have a left-navigation menu that comes and goes as you shrink and grow the browser window. Try it. Go into a course and shrink the browser window. You'll see the navigation menu disappear. Now grow the browser window and mouse over the left side of the window. You'll see an arrow that lets you make the navigation menu visible again. But, if your B2 is displaying content on the course page, without the bbNG: pageHeader and bbNG:breadcrumbBar tags, the left-navigation menu will disapper and you will not be able to get it back. Unless you reload the page.
This B2 has a sample course tool link which works correctly. GitHub - mark-b-kauffman/bbdn-bblogbackb2: Demo the use of Logback to create log files.
Here's a video demonstration: Dropbox - 2018-10-12_16-08-30.UseBreadcrumbs.KeepTheNavMenu.mp4
Leave some breadcrumbs!