diff --git a/src/NHibernate.Test/Async/NHSpecificTest/NH3506/Fixture.cs b/src/NHibernate.Test/Async/NHSpecificTest/NH3506/Fixture.cs
new file mode 100644
index 00000000000..3ee9ae36268
--- /dev/null
+++ b/src/NHibernate.Test/Async/NHSpecificTest/NH3506/Fixture.cs
@@ -0,0 +1,120 @@
+//------------------------------------------------------------------------------
+// <auto-generated>
+//     This code was generated by AsyncGenerator.
+//
+//     Changes to this file may cause incorrect behavior and will be lost if
+//     the code is regenerated.
+// </auto-generated>
+//------------------------------------------------------------------------------
+
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using NHibernate.SqlCommand;
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.NH3506
+{
+	using System.Threading.Tasks;
+	[TestFixture]
+	public class FixtureAsync : BugTestCase
+	{
+		private Department _department;
+
+		private Employee _employee1;
+
+		private Employee _employee2;
+
+		protected override void OnSetUp()
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				_department = new Department();
+
+				_employee1 = new Employee
+				{
+					Department = _department
+				};
+
+				_employee2 = new Employee();
+
+				session.Save(_department);
+				session.Save(_employee1);
+				session.Save(_employee2);
+
+				tx.Commit();
+			}
+		}
+
+		protected override void OnTearDown()
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				session.Delete(_department);
+				session.Delete(_employee1);
+				session.Delete(_employee2);
+
+				tx.Commit();
+			}
+		}
+
+		[Theory]
+		public async Task Querying_Employees_LeftJoining_On_Departments_Should_Return_All_Employees_HQLAsync(bool enableFilter)
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				if (enableFilter)
+					session.EnableFilter("ValidAtFilter").SetParameter("CurrentDate", DateTime.UtcNow);
+
+				var employees = await (session.CreateQuery("select e from Employee e left join e.Department d")
+					.ListAsync<Employee>());
+
+				Assert.That(employees.Count, Is.EqualTo(2));
+
+				await (tx.CommitAsync());
+			}
+		}
+
+		[Theory]
+		public async Task Querying_Employees_LeftJoining_On_Departments_Should_Return_All_Employees_ICriteriaAsync(bool enableFilter)
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				if (enableFilter)
+					session.EnableFilter("ValidAtFilter").SetParameter("CurrentDate", DateTime.UtcNow);
+
+				var employees = await (session.CreateCriteria<Employee>()
+					.CreateCriteria("Department", JoinType.LeftOuterJoin)
+					.ListAsync<Employee>());
+
+				Assert.That(employees.Count, Is.EqualTo(2));
+
+				await (tx.CommitAsync());
+			}
+		}
+
+		[Theory]
+		public async Task Querying_Employees_LeftJoining_On_Departments_Should_Return_All_Employees_QueryOverAsync(bool enableFilter)
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				if (enableFilter)
+					session.EnableFilter("ValidAtFilter").SetParameter("CurrentDate", DateTime.UtcNow);
+
+				var employees = await (session.QueryOver<Employee>()
+					.JoinQueryOver(x => x.Department, JoinType.LeftOuterJoin)
+					.ListAsync());
+
+				Assert.That(employees.Count, Is.EqualTo(2));
+
+				await (tx.CommitAsync());
+			}
+		}
+	}
+}
diff --git a/src/NHibernate.Test/NHSpecificTest/NH3506/BaseClass.cs b/src/NHibernate.Test/NHSpecificTest/NH3506/BaseClass.cs
new file mode 100644
index 00000000000..1e28c529c42
--- /dev/null
+++ b/src/NHibernate.Test/NHSpecificTest/NH3506/BaseClass.cs
@@ -0,0 +1,9 @@
+using System;
+
+namespace NHibernate.Test.NHSpecificTest.NH3506
+{
+	public class BaseClass
+	{
+		public virtual Guid Id { get; set; }
+	}
+}
diff --git a/src/NHibernate.Test/NHSpecificTest/NH3506/Department.cs b/src/NHibernate.Test/NHSpecificTest/NH3506/Department.cs
new file mode 100644
index 00000000000..f3d3a833a4c
--- /dev/null
+++ b/src/NHibernate.Test/NHSpecificTest/NH3506/Department.cs
@@ -0,0 +1,6 @@
+namespace NHibernate.Test.NHSpecificTest.NH3506
+{
+	public class Department : BaseClass
+	{
+	}
+}
diff --git a/src/NHibernate.Test/NHSpecificTest/NH3506/Employee.cs b/src/NHibernate.Test/NHSpecificTest/NH3506/Employee.cs
new file mode 100644
index 00000000000..7e15c859882
--- /dev/null
+++ b/src/NHibernate.Test/NHSpecificTest/NH3506/Employee.cs
@@ -0,0 +1,7 @@
+namespace NHibernate.Test.NHSpecificTest.NH3506
+{
+	public class Employee : BaseClass
+	{
+		public virtual Department Department { get; set; }
+	}
+}
diff --git a/src/NHibernate.Test/NHSpecificTest/NH3506/Fixture.cs b/src/NHibernate.Test/NHSpecificTest/NH3506/Fixture.cs
new file mode 100644
index 00000000000..ffc6a821136
--- /dev/null
+++ b/src/NHibernate.Test/NHSpecificTest/NH3506/Fixture.cs
@@ -0,0 +1,109 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using NHibernate.SqlCommand;
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.NH3506
+{
+	[TestFixture]
+	public class Fixture : BugTestCase
+	{
+		private Department _department;
+
+		private Employee _employee1;
+
+		private Employee _employee2;
+
+		protected override void OnSetUp()
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				_department = new Department();
+
+				_employee1 = new Employee
+				{
+					Department = _department
+				};
+
+				_employee2 = new Employee();
+
+				session.Save(_department);
+				session.Save(_employee1);
+				session.Save(_employee2);
+
+				tx.Commit();
+			}
+		}
+
+		protected override void OnTearDown()
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				session.Delete(_department);
+				session.Delete(_employee1);
+				session.Delete(_employee2);
+
+				tx.Commit();
+			}
+		}
+
+		[Theory]
+		public void Querying_Employees_LeftJoining_On_Departments_Should_Return_All_Employees_HQL(bool enableFilter)
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				if (enableFilter)
+					session.EnableFilter("ValidAtFilter").SetParameter("CurrentDate", DateTime.UtcNow);
+
+				var employees = session.CreateQuery("select e from Employee e left join e.Department d")
+					.List<Employee>();
+
+				Assert.That(employees.Count, Is.EqualTo(2));
+
+				tx.Commit();
+			}
+		}
+
+		[Theory]
+		public void Querying_Employees_LeftJoining_On_Departments_Should_Return_All_Employees_ICriteria(bool enableFilter)
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				if (enableFilter)
+					session.EnableFilter("ValidAtFilter").SetParameter("CurrentDate", DateTime.UtcNow);
+
+				var employees = session.CreateCriteria<Employee>()
+					.CreateCriteria("Department", JoinType.LeftOuterJoin)
+					.List<Employee>();
+
+				Assert.That(employees.Count, Is.EqualTo(2));
+
+				tx.Commit();
+			}
+		}
+
+		[Theory]
+		public void Querying_Employees_LeftJoining_On_Departments_Should_Return_All_Employees_QueryOver(bool enableFilter)
+		{
+			using (var session = OpenSession())
+			using (var tx = session.BeginTransaction())
+			{
+				if (enableFilter)
+					session.EnableFilter("ValidAtFilter").SetParameter("CurrentDate", DateTime.UtcNow);
+
+				var employees = session.QueryOver<Employee>()
+					.JoinQueryOver(x => x.Department, JoinType.LeftOuterJoin)
+					.List();
+
+				Assert.That(employees.Count, Is.EqualTo(2));
+
+				tx.Commit();
+			}
+		}
+	}
+}
diff --git a/src/NHibernate.Test/NHSpecificTest/NH3506/Mappings.hbm.xml b/src/NHibernate.Test/NHSpecificTest/NH3506/Mappings.hbm.xml
new file mode 100644
index 00000000000..1d686b9d3a4
--- /dev/null
+++ b/src/NHibernate.Test/NHSpecificTest/NH3506/Mappings.hbm.xml
@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
+                   namespace="NHibernate.Test.NHSpecificTest.NH3506"
+                   assembly="NHibernate.Test">
+
+	<class name="BaseClass">
+		<id name="Id">
+			<generator class="guid.comb" />
+		</id>
+		<discriminator column="discriminator" type="String" />
+
+		<subclass name="Employee" discriminator-value="Emp">
+			<many-to-one name="Department" class="Department" />
+		</subclass>
+
+		<subclass name="Department" discriminator-value="Dep">
+		</subclass>
+	</class>
+
+	<filter-def name="ValidAtFilter">
+		<filter-param name="CurrentDate" type="DateTime" />
+		<![CDATA[ValidAt = :CurrentDate]]>
+	</filter-def>
+
+</hibernate-mapping>
diff --git a/src/NHibernate/Loader/JoinWalker.cs b/src/NHibernate/Loader/JoinWalker.cs
index fe3ea666811..372ef8bed73 100644
--- a/src/NHibernate/Loader/JoinWalker.cs
+++ b/src/NHibernate/Loader/JoinWalker.cs
@@ -687,7 +687,9 @@ protected JoinFragment MergeOuterJoins(IList<OuterJoinableAssociation> associati
 							outerjoin.ToFromFragmentString.IndexOfCaseInsensitive(manyToOneFilterFragment) == -1;
 						if (joinClauseDoesNotContainsFilterAlready)
 						{
-							outerjoin.AddCondition(manyToOneFilterFragment);
+							// Ensure that the join condition is added to the join, not the where clause.
+							// Adding the condition to the where clause causes left joins to become inner joins.
+							outerjoin.AddFromFragmentString(new SqlString(manyToOneFilterFragment));
 						}
 					}
 				}