I found the problem!! :D
It wasn't cache, I tried it too, but it was the same.
All that I did was put permission READ just to page "sidebar" and assign it to the group @ALL.
This made appear the sidebar :nuts: :rolleyes:
I could understand it for this link:
https://www.dokuwiki.org/plugin:indexmenu#about_acls
And imagine that because admin can see all, even without permissions. but for users I had to specify it and create the permission
Thanks Michael!