Document Set with folders

Hello,

I'm having an issue in SharePoint 2013 on-premise using the 2010 layouts. this started to happen with a migrated site collection from 2010, but then I tried with a clean site collection on 2013, but using the template of 2010, and it keeps happening, so this really seems to be a bug of SP2013 using the layout of 2010.

the steps to replicate the issue are:

1. create a site collection, using the 2010 template version
2. on a document library, activate management of content types, add the content type "Document Set"
3. create a document set, and inside create a folder, with sub folder, with sub folder... until you get the error. this should break at second or third folder level.

this is somehow generating a wrong html code in the "docsethomepage.aspx", it is using an unexpected "&".

The problem is that this error is invalidating the entire page, so no client side features can be used (like the ribbon, or the breadcrumb) .

hope someone can help here. thanks.