Attributes in Unique constraint changing to a not null field

Version: Toad data modeler 5.5
Database: MS Sql Server 2014/16
I am creating a unique constraint. For this I added another key other than primary key and selected two attributes out of them one attribute is null.
When I finish adding the key it is changing the null attribute to not null.
I changed the settings for physical model allowing null in keys after looking into some other articles but no use.
I tried this by closing toad and starting it to see if the change in settings require a restart but still I get the same issue.
SQL Server allows to create a unique value for multiple attributes where one of them can have a null values allowed but not sure how to get this in toad
Is there any other place where I can create unique constraints - don’t think this is the case
How to create a composite unique key allowing null in one of the attributes


yes, you are right. Sql server allows to create unique constraint where one of the attributes is null and TDM allows it too. Check the option "Allow Null Attributes in Keys" as you did, open the entity properties, switch to the Attributes grid and manually uncheck options Not Null or go to the Attribute properties and uncheck it here.