Layout customisations are not propagated to other cluster nodes

I just updated Extranet to add an outage notice to the Main Layout in Administration > Layouts.

This appeared straight away on node 1 of Extranet, where I made the change, but didn't appear on node 2. Going to node 2, Administration, Layouts, I could see that the layout was changed. Clicking edit and save (without making any changes) on node 2 was enough to propagate the changes.

Likely cause is some non-distributed cache – perhaps we use a static HashMap or something, rather than the Coherence cache.