diff --git a/eng/packages/http-client-csharp-mgmt/generator/Azure.Generator.Management/src/Utilities/PropertyHelpers.cs b/eng/packages/http-client-csharp-mgmt/generator/Azure.Generator.Management/src/Utilities/PropertyHelpers.cs
index 84ec8a84dd36..4a9121c7b33c 100644
--- a/eng/packages/http-client-csharp-mgmt/generator/Azure.Generator.Management/src/Utilities/PropertyHelpers.cs
+++ b/eng/packages/http-client-csharp-mgmt/generator/Azure.Generator.Management/src/Utilities/PropertyHelpers.cs
@@ -135,11 +135,7 @@ public static MethodBodyStatement BuildGetter(bool? includeGetterNullCheck, Prop
 
         public static MethodBodyStatement? BuildSetterForSafeFlatten(bool includeSetterCheck, ModelProvider innerModel, PropertyProvider internalProperty, PropertyProvider innerProperty)
         {
-            if (innerProperty.Type.IsCollection)
-            {
-                return null;
-            }
-
+            // To not introduce breaking change, for collection types, we keep the setter for collection-type properties during safe flatten.
             var isOverriddenValueType = IsOverriddenValueType(innerProperty);
             var setter = new List<MethodBodyStatement>();
             var internalPropertyExpression = This.Property(internalProperty.Name);
diff --git a/eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/BarSettingsResourceData.cs b/eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/BarSettingsResourceData.cs
index 0ba95e94e4b7..66839da53e1b 100644
--- a/eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/BarSettingsResourceData.cs
+++ b/eng/packages/http-client-csharp-mgmt/generator/TestProjects/Local/Mgmt-TypeSpec/src/Generated/BarSettingsResourceData.cs
@@ -208,6 +208,10 @@ public IList<string> OptionalFlattenPropertyRandomCollectionProp
             {
                 return OptionalFlattenProperty is null ? default : OptionalFlattenProperty.RandomCollectionProp;
             }
+            set
+            {
+                OptionalFlattenProperty = new OptionalFlattenPropertyType(value);
+            }
         }
     }
 }