SQL for fetching associations is using "JOIN" instead of "LEFT JOIN"

[Yijun]

Hello I am using a DataModelFluentMetadataSource where all the metadata is defined.

The associations are defined with a nullable foreign key columns in my database, and mapped in the context as nullable columns.

This is my LINQ:

Context.Subjects.Where(x => x.NameCode.Contains(search) || (x.SubjectGroup == null ? false : x.SubjectGroup.Name.Contains(search)) || (x.SubjectCohort == null ? false : x.SubjectCohort.Name.Contains(search)));

This is my generated SQL:

SELECT  a.[SubjectID] AS COL1, a.[IsActive] AS COL2, a.[NameCode] AS COL3, a.[SubjectCohortID] AS COL4, a.[SubjectGroupID] AS COL5 FROM [Subjects] a JOIN [SubjectGoups] AS b ON (a.[SubjectGroupID] = b.[SubjectGroupID])JOIN [SubjectCohorts] AS c ON (a.[SubjectCohortID] = c.[SubjectCohortID]) WHERE (a.[NameCode] LIKE '%555%' OR b.[Name] LIKE '%555%' OR c.[Name] LIKE '%555%') ORDER BY COL1

This SQL does not return all the records that match the search.
This is how it should be:

SELECT  a.[SubjectID] AS COL1, a.[IsActive] AS COL2, a.[NameCode] AS COL3, a.[SubjectCohortID] AS COL4, a.[SubjectGroupID] AS COL5 FROM [Subjects] a LEFT JOIN [SubjectGoups] AS b ON (a.[SubjectGroupID] = b.[SubjectGroupID]) LEFT JOIN [SubjectCohorts] AS c ON (a.[SubjectCohortID] = c.[SubjectCohortID]) WHERE (a.[NameCode] LIKE '%555%' OR b.[Name] LIKE '%555%' OR c.[Name] LIKE '%555%') ORDER BY COL1

This SQL returns all records correctly.
How can I force it to use "LEFT OUTER JOIN"?
Any help would be appreciated.

Regards,
Yijun