Data Store - change the data source

I have an exsiting Data store with Data Source (DS1) , DS1 is legacy. I cloned the database from the data source for this DS1 and put this onto new Data Source (DS2).
When I go to the Data Store and try to change the Data Source from DS1 to DS2 - it complains about tables not existing when you try to verify.
Also, the Appian generated DDL has multiple Nulls - causing SQL to error on creating the schema. Please suggest how to point to a new data source successfully.

eg: create table [Instructors] (
[InstructorID] int identity not null,
[InstructorQuals] VARCHAR(MAX) NULL null,
[FirstName] VARCHAR(50) NULL null,
[LastName] VARCHAR(50) NULL null,
primary key ([InstructorID])
);

OriginalPostID-257045