Think I could simulate this. Are you getting a similar exception in your logs ?

org.picketlink.idm.IdentityManagementException: Could not find AttributedType [class org.jboss.as.quickstarts.picketlink.angularjs.security.model.MyUser] with the given identifier [04219421-5be5-4f20-bda2-3026fa27e41b] for Partition [d9d9b67f-42f9-4700-af11-3357b49a3704]