Child nodetype sorting does not work in document editor when pressing 'up' icon

When I press the 'up' icon for a multiple and orderable node, the actual move only works after pressing 'save'. If you press the move up icon multiple times before saving you will end up with the following error message:

WARN - NodeTemplateProvider - could not find org.hippoecm.frontend.model.JcrNodeModel@9712d0[
itemModel=org.hippoecm.frontend.model.JcrItemModel@545283[
path=/content/documents/mysite/nl/nieuwsberichten/foo/foo/3]/mysite:contentblock[2]
]
]