diff --git a/src/Forms/SearchableDropdownTrait.php b/src/Forms/SearchableDropdownTrait.php
index 5931912f9d2..c692eaffe28 100644
--- a/src/Forms/SearchableDropdownTrait.php
+++ b/src/Forms/SearchableDropdownTrait.php
@@ -262,6 +262,10 @@ public function setIsSearchable(bool $isSearchable): static
      */
     public function getSource(): array
     {
+        // Source will be unused when lazy-loading so just return an empty array
+        if ($this->getIsLazyLoaded()) {
+            return [];
+        }
         return $this->getListMap($this->sourceList);
     }
 
diff --git a/tests/php/Forms/SearchableDropdownTraitTest.php b/tests/php/Forms/SearchableDropdownTraitTest.php
index d6f3aae4cd4..4a2ad9ca815 100644
--- a/tests/php/Forms/SearchableDropdownTraitTest.php
+++ b/tests/php/Forms/SearchableDropdownTraitTest.php
@@ -217,4 +217,28 @@ public function testGetSchemaDataDefaults(): void
         $this->assertSame('My placeholder', $schema['placeholder']);
         $this->assertFalse($schema['searchable']);
     }
+
+    public function provideGetSource(): array
+    {
+        return [
+            'lazyLoad' => [
+                'isLazyLoaded' => true,
+                'expected' => 0,
+            ],
+            'not lazyLoad' => [
+                'isLazyLoaded' => false,
+                'expected' => 3,
+            ],
+        ];
+    }
+
+    /**
+     * @dataProvider provideGetSource
+     */
+    public function testGetSource(bool $isLazyLoaded, int $expected): void
+    {
+        $field = new SearchableDropdownField('MyField', 'MyField', Team::get());
+        $field->setIsLazyLoaded($isLazyLoaded);
+        $this->assertCount($expected, $field->getSource());
+    }
 }