diff --git a/src/core/etl/src/Flow/ETL/GroupBy.php b/src/core/etl/src/Flow/ETL/GroupBy.php
index d2217f3f6..cc65430fc 100644
--- a/src/core/etl/src/Flow/ETL/GroupBy.php
+++ b/src/core/etl/src/Flow/ETL/GroupBy.php
@@ -57,8 +57,6 @@ public function aggregate(AggregatingFunction ...$aggregator) : void
     public function group(Rows $rows) : void
     {
         if ($this->pivot) {
-            $this->pivotColumns = [];
-
             foreach ($rows as $row) {
                 try {
                     $pivotValue = $row->valueOf($this->pivot);