Relationship names are disappearing when new table is added to Main Diagram through Reverse Engineering

Relationship names are disappearing when new table is added to Main Diagram through Reverse Engineering:

We have added one table through reverse engineering to Main Diagram. Table got added successfully. But all relationship names for links for disappeared as soon we added the table to Main Diagram.

This will be major issue in case we have 100s of tables in the Diagram.

Please suggest why this issue occurs and the solution.