diff --git a/reportbuilder/classes/local/helpers/custom_fields.php b/reportbuilder/classes/local/helpers/custom_fields.php
index 616d114f80a..0f39a1c59ca 100644
--- a/reportbuilder/classes/local/helpers/custom_fields.php
+++ b/reportbuilder/classes/local/helpers/custom_fields.php
@@ -179,9 +179,13 @@ class custom_fields {
                     ->add_join($this->get_table_join($field))
                     ->add_field($datafieldsql, $datafield)
                     ->add_fields($selectfields)
+                    ->add_field($this->tablefieldalias, 'tablefieldalias')
                     ->set_type($columntype)
                     ->set_is_sortable($columntype !== column::TYPE_LONGTEXT)
                     ->add_callback(static function($value, stdClass $row, field_controller $field): string {
+                        if ($row->tablefieldalias === null) {
+                            return '';
+                        }
                         return (string) data_controller::create(0, $row, $field)->export_value();
                     }, $field)
                     // Important. If the handler implements can_view() function, it will be called with parameter $instanceid=0.
diff --git a/reportbuilder/tests/local/helpers/custom_fields_test.php b/reportbuilder/tests/local/helpers/custom_fields_test.php
index ae38b8ddb59..477f3d02474 100644
--- a/reportbuilder/tests/local/helpers/custom_fields_test.php
+++ b/reportbuilder/tests/local/helpers/custom_fields_test.php
@@ -28,7 +28,7 @@ use core_reportbuilder\local\filters\select;
 use core_reportbuilder\local\filters\text;
 use core_reportbuilder\local\report\column;
 use core_reportbuilder\local\report\filter;
-use core_course\reportbuilder\datasource\courses;
+use core_course\reportbuilder\datasource\{categories, courses};
 
 defined('MOODLE_INTERNAL') || die();
 
@@ -177,7 +177,7 @@ class custom_fields_test extends core_reportbuilder_testcase {
         $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
         $report = $generator->create_report(['name' => 'Courses', 'source' => courses::class, 'default' => 0]);
 
-        // Add user profile field columns to the report.
+        // Add custom field columns to the report.
         $generator->create_column(['reportid' => $report->get('id'), 'uniqueidentifier' => 'course:fullname']);
         $generator->create_column(['reportid' => $report->get('id'), 'uniqueidentifier' => 'course:customfield_text']);
         $generator->create_column(['reportid' => $report->get('id'), 'uniqueidentifier' => 'course:customfield_textarea']);
@@ -197,6 +197,34 @@ class custom_fields_test extends core_reportbuilder_testcase {
         ], array_values($content[0]));
     }
 
+    /**
+     * Test that adding custom field columns to report returns expected default values for fields
+     */
+    public function test_custom_report_content_column_defaults(): void {
+        $this->resetAfterTest();
+
+        $this->generate_customfields();
+
+        $category = $this->getDataGenerator()->create_category(['name' => 'Zebras']);
+        $course = $this->getDataGenerator()->create_course(['category' => $category->id]);
+
+        /** @var core_reportbuilder_generator $generator */
+        $generator = $this->getDataGenerator()->get_plugin_generator('core_reportbuilder');
+        $report = $generator->create_report(['name' => 'Categories', 'source' => categories::class, 'default' => 0]);
+
+        // Add custom field columns to the report.
+        $generator->create_column(['reportid' => $report->get('id'), 'uniqueidentifier' => 'course_category:name',
+            'sortenabled' => 1]);
+        $generator->create_column(['reportid' => $report->get('id'), 'uniqueidentifier' => 'course:fullname']);
+        $generator->create_column(['reportid' => $report->get('id'), 'uniqueidentifier' => 'course:customfield_select']);
+
+        $content = $this->get_custom_report_content($report->get('id'));
+        $this->assertEquals([
+            ['Category 1', '', ''],
+            [$category->name, $course->fullname, 'Cat'],
+        ], array_map('array_values', $content));
+    }
+
     /**
      * Data provider for {@see test_custom_report_filter}
      *