v2017.3: SQL Server 2012 database - foreign key update/delete rules ALWAYS "no action"

Hi,

For some reason, when I look at my foreign key definitions in DataGrip, the update rule and delete rule are always showing no action. This occurs regardless of whether I am in the table editor or the DDL view; whether I use the Microsoft driver or the jTds driver.

Has anybody else noticed the same? Have I missed a setting somewhere?

Thanks for any advice you can give. :)