Edmx file not updating
Per the following question: How do I propagate database changes to my file?One of the answers seems to say the same thing, that you need to remove the entity and add it back in.
When you updated the database using the update model wizard, it updated the storage model in the file and not the conceptual model.Installing the EF6 Nu Get package should automatically remove any references to System. The namespaces for Db Context and Code First types have not changed. This means for many applications that use EF 4.1 or later you will not need to change anything. This means you may need to update your directives to build against EF6. When changes are made to the definition of existing objects, only the storage model is updated; the conceptual model is not updated.For a complete description of changes that are made by the update model wizard, please see the "Changes Made to an File by the Update Model Wizard" link above.