Did anyone find the solution to this? I notice that logging out of Alfresco allows me to create content from another schema so it's a workaround for now but probably not ideal when in full production use by a editorial team.
Tested on Labs v 3.0
Seems something in the XFormSession in XFormsBean is hanging onto the schema and the previous form instance, I also get duplicated content (mentioned in another post) caused and alleviated in the same way - log out and the problem goes.