Assume that you create a primary key or a unique index that consists of more than one column in a table in Microsoft SQL Server 2014 and 2016. When you run the sp_special_columns system stored procedure on the table, not all the participating columns are returned.
Note This issue may occur if you have one or more columns deleted from the table.
Service pack information for SQL Server
This update is fixed in the following service packs for SQL Server:
Service packs are cumulative. Each new service pack contains all the fixes that are in previous service packs, together with any new fixes. Our recommendation is to apply the latest service pack and the latest cumulative update for that service pack. You do not have to install a previous service pack before you install the latest service pack. Use Table 1 in the following article for finding more information about the latest service pack and latest cumulative update.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
Learn about the terminologythat Microsoft uses to describe software updates.