Resolve error "Unable to save Publication because a referenced item does not exist" in EngageOne Designer

Product Feature: Data Map/Data Dictionary

Operating System:Windows 7

Database: SQL 2008 R2

Issue

User receives the following error "Unable to save Publication because a referenced item does not exist".  

In this case the Data Map that was not deleted was not being noticed by the publication. 

Cause

The problem, was that the system thought the Data Map did not exist, however, it had not been deleted.  

Resolution

UPDATED: October 31, 2017
These steps will fix the issue:
1.  Create a new Project from Version - New Project.
2.  Merge the Master to New Project - Versions - Merge  (Compare then merge).
3.  Verify that you can see the missing file.
4.  Try to make a change to the document and save it.
5.  Merge New Project back to Old Project.