hi,
On the hotfix Nuxeo 5.6.0-HF30, you added new facets "MasterPublishSpace" and "PublishSpace" to document type "SectionRoot" and "Section", I find the idea very well but you should say before installation in production.
Because I redefined these types of documents in Nuxeo Studio, and not having the facets.
I wasn't able published in Nuxeo. The Tree of publication did not appear .... 😞
After the installation :

After modification in Nuxeo Studio :

I added the facets in Studio and everything works again
Document Facets Registry Editor :
{
facets: [
{
id: "MasterPublishSpace",
description: "Facet MasterPublishSpace pour les sectionroots",
},
{
id: "PublishSpace",
description: "Facet PublishSpace pour les sections",
}
]
}