Azure SQL Database import issue in Visual Studio 2013

Hi.,

I have recently created Azure SQL and Configure Sync to On-Premises database.. last week the Designer worked correctly with no issue.

from yesterday I have noticed that I cannot re-design the table.. I am getting following error message:

 I search this issue in google & found that, this issue related to SSDT. I have repaired the SSDT for Visual studio 2013. now the issue is import database model taking long time. nearly 1 hour yet database is not imported.

can anyone know, how to resolve this...

Thanks