Fixed issue #1856 as a follow up of issue #949: Unpermitted customer field in customer create ticket view.

app/assets/javascripts/app/lib/app_post/auth.coffee

@@ -150,10 +150,6 @@ class App.Auth
 
     # clear all in-memory data of all App.Model's
     for model_key, model_object of App
-      if _.isFunction(model_object.resetCallbacks)
-        model_object.resetCallbacks()
-      if _.isFunction(model_object.resetAttributes)
-        model_object.resetAttributes()
       if _.isFunction(model_object.clearInMemory)
         model_object.clearInMemory()
 

app/assets/javascripts/app/models/_application_model.coffee

@@ -816,17 +816,16 @@ set new attributes of model (remove already available attributes)
     )
 
   @clearInMemory: ->
-    return if !@className
+    # reset callbacks to session based functions
+    @resetCallbacks()
 
     # reset attributes to prevent cached forms on relogin
-    if !_.isEmpty(App[@className].org_configure_attributes)
-      App[@className].configure_attributes = App[@className].org_configure_attributes
+    @resetAttributes()
 
     # reset cached values of model
-    App[@className].deleteAll()
+    @deleteAll()
 
   @updateAttributes: (attributes) ->
-    return if !@className
     if _.isEmpty(@org_configure_attributes)
 
       # use jquery instead of ._clone() because we need a deep copy of the obj