diff --git a/backend/plugins/customize/tasks/customized_fields_extractor.go b/backend/plugins/customize/tasks/customized_fields_extractor.go
index 7bd1d932d7b..beb1f88df5c 100644
--- a/backend/plugins/customize/tasks/customized_fields_extractor.go
+++ b/backend/plugins/customize/tasks/customized_fields_extractor.go
@@ -142,7 +142,9 @@ func extractCustomizedFields(ctx context.Context, d dal.Dal, table, rawTable, ra
 				}
 			}
 		default:
-			return nil
+			// orphaned/NULL raw data (LEFT JOIN found no matching raw record): skip this
+			// row and keep scanning, instead of aborting the whole subtask.
+			continue
 		}
 
 		if len(updates) > 0 {
diff --git a/backend/plugins/customize/tasks/customized_fields_extractor_test.go b/backend/plugins/customize/tasks/customized_fields_extractor_test.go
new file mode 100644
index 00000000000..4cbd2d75539
--- /dev/null
+++ b/backend/plugins/customize/tasks/customized_fields_extractor_test.go
@@ -0,0 +1,83 @@
+/*
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements.  See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to You under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License.  You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package tasks
+
+import (
+	"context"
+	"testing"
+
+	"github.com/apache/incubator-devlake/core/dal"
+	mockdal "github.com/apache/incubator-devlake/mocks/core/dal"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/mock"
+)
+
+// TestExtractCustomizedFieldsSkipsOrphanedRows is a regression test for the case where a
+// domain-layer row's `_raw_data_id` has no matching raw record (LEFT JOIN yields NULL data).
+// Such a row must be skipped and extraction must continue with the remaining rows, instead of
+// aborting the whole scan on the first orphaned row.
+func TestExtractCustomizedFieldsSkipsOrphanedRows(t *testing.T) {
+	mockRows := new(mockdal.Rows)
+	mockRows.On("Next").Return(true).Times(2)
+	mockRows.On("Next").Return(false).Once()
+	mockRows.On("Close").Return(nil).Once()
+
+	mockDal := new(mockdal.Dal)
+	mockDal.On("GetColumns", mock.Anything, mock.Anything).Return([]dal.ColumnMeta{}, nil)
+	mockDal.On("Cursor", mock.Anything).Return(mockRows, nil).Once()
+
+	// Row 1 is orphaned: no matching raw record, so `data` is NULL (nil). It must be skipped.
+	mockDal.On("Fetch", mock.Anything, mock.Anything).Run(func(args mock.Arguments) {
+		dst := args.Get(1).(*map[string]interface{})
+		*dst = map[string]interface{}{
+			"id":           "row-orphaned",
+			"_raw_data_id": int64(1),
+			"data":         nil,
+		}
+	}).Return(nil).Once()
+	// Row 2 has valid raw data and matches the filter; it must still be processed.
+	mockDal.On("Fetch", mock.Anything, mock.Anything).Run(func(args mock.Arguments) {
+		dst := args.Get(1).(*map[string]interface{})
+		*dst = map[string]interface{}{
+			"id":           "row-valid",
+			"_raw_data_id": int64(2),
+			"data":         `{"name":"hello"}`,
+		}
+	}).Return(nil).Once()
+
+	execCalls := 0
+	mockDal.On("Exec", mock.Anything, mock.Anything).Run(func(args mock.Arguments) {
+		execCalls++
+	}).Return(nil)
+
+	err := extractCustomizedFields(
+		context.Background(),
+		mockDal,
+		"boards", // non-issues table -> simple column update path
+		"_raw_jira_api_issues",
+		`{"ConnectionId":1`,
+		map[string]string{"x_test": "name"},
+	)
+
+	assert.Nil(t, err)
+	// The valid row after the orphaned one must have been updated exactly once.
+	// Before the fix, the orphaned row hit `default: return nil` and aborted the scan,
+	// so Exec was never called.
+	assert.Equal(t, 1, execCalls)
+	mockDal.AssertExpectations(t)
+}