What do you mean it is not added to the toolbar? Do you mean that its toolbar is not visible? Or its position is not saved after restart?
I think the option is saved because when I open C::B 17.12 the BrowseTracker toolbar is added to the toolbar. But when I open the svn build it doesn't.
By not added to the toolbar I mean that buttons enclosed in a red rectangle in the attached image are not shown.
I've tested the IncrementalSearch and ThreadedSearch plugins and they work correctly.
EDIT: Looks like C::B fails to load the setting on startup, how can I check that?