The Help file (/help/source/text/shared/01/notebook_bar.xhp) currently indicates that the Notebookbar facilities are disabled by default, until you choose Tools - Options - LibreOffice - Advanced and select the Enable experimental features checkbox.
This is no longer the case and some of the features are enabled in Writer, Calc, Draw and Impress by default, without selecting the Enable experimental features checkbox.
The help information should be updated accordingly.
delete line 49 of given file.
Olivier Hallot committed a patch related to this issue.
It has been pushed to "master":
tdf#133109 Update notebook bar Hhelp page
A polite ping to Olivier Hallot:
Is this bug fixed? if so, could you please close it as RESOLVED FIXED ?
Otherwise, Could you please explain what's missing?