Hello,
Bug is still here. I have found cause and alter Frappe code on my bench installation.
Cause : Sidebar items group has rewritten when Context is build on Webpage Doctype.
Solution :
On frappe/website/doctype/web_page/webpage.py, line 74 :
if self.show_sidebar:
if self.website_sidebar:
sidebar = frappe.get_doc('Website Sidebar', self.website_sidebar)
context.sidebar_items = sidebar.get_items()
else:
context.sidebar_items = get_sidebar_items(self.website_sidebar)