Sync issues between 2 nodes in a cluster when editing a Panel xobject

Here's what we did 2 times on xwiki.org:

• Edited this panel page http://www.xwiki.org/xwiki/bin/view/Panels/AdminGuide with the inline editor
• Made a change to it and hit Save
• Then checked the Navigation Panel displayed on the left on both node1 and node2 and got different results (on one node it's empty and on the other it's not empty):
  • http://platform.xwikiorg-node1.xwikisas.com/xwiki/bin/view/AdminGuide/
  • http://platform.xwikiorg-node2.xwikisas.com/xwiki/bin/view/AdminGuide/

If we restart the nodes, then it's ok again.