Sidebar appears at each page display

We are migrating from Theme builder 3 to 4.03

In the former version, the leftsidebar, remained at the same position (opened or closed) when dowloading a new page. Now it opens at each new page. I have seen an option in the layout manager but it seems not working.
The issue is the same in a copy of the default theme.

More..., when I close the sidebar and open it again, the sidebar is empty. When I close it again, the content appears during a short time and then the sidebar is closed. (same issue in the Default)

Could you help me please.

August 31th: the issue desappears alone after a relaunch of Confluence (sorry I cannot add a comment, there is a browser issue).