Delete function not working within a transaction pdo php mysql - php

Question

I am having similar problems as this colleague: similar problem
I am surprised that a Delete function within a transaction with pdo does not behave properly. If I use the delete function alone in a pdo it works perfectly but when I combine the delete function with an update function in a transaction it stops working (only first query works). I have tried all the answer and tips from the old thread but nothing seems to work. Can someone help me here?
The code that I am working with:
function denyactionevent(){
try {
$$this->setAttribute(PDO::ATTR_AUTOCOMMIT, true);
$$this->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$this->conn->beginTransaction();
// product update query
$query = "UPDATE
" . $this->table_name . "
SET
accepted = :accepted
WHERE
id = :id";
// prepare query statement
$stmt = $this->conn->prepare($query);
// bind variable values
$stmt->bindParam(':accepted', $this->accepted);
$stmt->bindParam(':id', $this->id);
// execute the query
$stmt->execute();
$query2 = "DELETE
FROM event_case
WHERE reference = :id
";
// prepare query statement
$stmt = $this->conn->prepare($query2);
// bind values
$stmt->bindParam(':id', $this->id);
// execute the query
$stmt->execute();
$this->conn->commit();
return true;
} catch (Exception $e) {
$stmt->rollBack();
return false;
}
}