Newly added navigation elements (spaces) disappearing
Problem
Some newly added elements (Confluence spaces) in the navigation disappear a few minutes after we've created them.
They also disappear for users who have enough rights to see the linked space.
Solution
You are experiencing the following bug: https://communardo.atlassian.net/browse/CSSP-321
When a Confluence administrator who cannot see all Confluence spaces edits the navigation and saves it, Confluence spaces the admin does not have access to disappear.
Workaround
Make sure that the SubSpace navigation is only edited by users who belong to the confluence-administrators group and can therefore see all Confluence spaces.
The issue is fixed now.