Auto-Increment versus Identity

I am using DG 2017.3. Trying to "Modify Table" in SQL Server 2008 to add auto-increment to an INT PRIMARY KEY column. It won't enable the "Execute" button and tells me right inside the dialog: 

-- SQL Server doesn't support adding auto increment constraints

Wait, what? Sure it does! It's called IDENTITY.

Exited DG, used SQL Server Management Studio to modify the column to add the IDENTITY constraint.

Back in DG, synchronized, going to "Modify Table": "Auto inc" checkbox is checked. So it does support auto-inc after all...?

Things like this undermine the trust in DG as a viable tool to manage all databases. 

Regards,
Andrew Wozniewicz