OK, I have it… deactivate secondary nav in the blog post…
But this is very stupid for me… my blog have nearly 300 posts where I have to make this manualy…
If you view one of the pages where this is happening and click “Customize” in the admin bar, then go to “Customize > Layout > Sidebars” – what setting do you have set?
It looks like you might have Content / Sidebar / Sidebar set.