mysqli_commit() is called instead of mysqli_rollback() in prepared statement

Question

This is the queries:

/* ALL THE QUERIES */
$sql_update = "UPDATE tbl_usulan_gb_detail SET
                status = ? ,
                scan_hasil_skgb = ?,
                tgl_selesai = ?,
                no_sk_baru = ?,
                tgl_sk_baru = ?,
                status_koreksi=?
            WHERE 
               id_usulan_gb_detail =?"; 
$sql_select1 = "SELECT a.*,b.* 
                FROM tbl_usulan_gb_detail a
                LEFT JOIN tbl_usulan_gb b ON b.id_usulan = a.id_usulan
                WHERE a.id_usulan_gb_detail = ? ";
$sql_select2 = "SELECT * FROM tbl_pejabat_penandatangan WHERE id = ?";
$sql_insert1 = "INSERT INTO tblriwayatgaji (
                id_pegawai,
                NIP,
                TMTGaji,
                NOSKGaji,
                TglSKGaji,
                PejabatSK,
                tgl_sk_usulan,
                mkg_tahun,
                mkg_bulan
                )VALUES(?,?,?,?,?,?,?,?,'?')"; // <----TEST ('') at the last of (?) would throw an error
$sql_select3 = "SELECT * FROM tblriwayatgaji WHERE NIP = ? OR id_pegawai=? AND TMTGaji =? ORDER BY id_riwayat_gaji DESC";
$sql_insert2 = "INSERT INTO 
              tbl_pegawai_upload_detail(id_pegawai,id_jenis,id_riwayat,scan_sk,catatan_upload)
            VALUES(?,?,?,?,?)";
/* END OF QUERIES */

And this is the transaction :

/*   NEW WITH EXCEPTION HANDLER   */
try {

    $mysqli->autocommit(false);

    // Update status column of tbl_usulan_gb_detail to 1
    $stmt = $mysqli->prepare($sql_update);
    $status = 1;
    $status_koreksi = 0;
    $tgl_selesai = date("Y-m-d");
    $stmt->bind_param("issssii", $status, $nama_file, $tgl_selesai, $no_sk, $tgl_sk, $status_koreksi, $id_usulan_gb_detail);
    //$stmt->execute(); // execute() is silently error :(
    if (!$stmt->execute()) {
        something_wrong(htmlspecialchars($mysqli->error));
        $mysqli->rollback();
        exit();
    }

    // Get data from tbl_usulan_gb_detail
    $stmt = $mysqli->prepare($sql_select1);
    $stmt->bind_param("i", $id_usulan_gb_detail);
    //$stmt->execute(); // execute() is silently error :(
    if (!$stmt->execute()) {
        something_wrong(htmlspecialchars($mysqli->error));
        exit();
    }
    $result = $stmt->get_result();
    $ds = $result->fetch_assoc();
    $nip = $ds["nip"];
    $id_pegawai = detail_pegawai_by_nip($ds["nip"],"id_pegawai"); // get the id of pegawai based on inserted nip
    $tmt_baru = $ds["tmt_baru"];
    $no_sk_usulan = $ds["no_sk_baru"];
    $tgl_sk_usulan = $ds["tgl_sk_baru"];//
    $mkg_tahun_baru = $ds["tahun_baru"];
    $mkg_bulan_baru = $ds["bulan_baru"];
    $scan_hasil_skgb = $ds["scan_hasil_skgb"]; //gak ada dipakai dibawah?

    // Get jabatan and daerah
    $stmt->prepare($sql_select2);
    $stmt->bind_param("i", $id=1);
    //$stmt->execute();// execute() is silently error :(
    if (!$stmt->execute()) {
        something_wrong(htmlspecialchars($mysqli->error));
        exit();
    }
    $result = $stmt->get_result();
    $peneken = $result->fetch_assoc();
    $nama_peneken = $peneken["jabatan"]." ".$peneken["daerah"];//"KEPALA BADAN KEPEGAWAIAN DAERAH KOTA MEDAN";


    // Insert data into tblriwayatgaji table
    if(!isset($tgl_usulan)){ // set tgl_sk_usulan in tblriwayatgaji (NOT NULL)
        $tgl_usulan = "0000-00-00";
    }
    $stmt = $mysqli->prepare($sql_insert1);             
    $stmt->bind_param("issssssss", $id_pegawai, $nip, $tmt_baru, $no_sk_usulan, $tgl_sk_usulan, $nama_peneken, $tgl_usulan, $mkg_tahun_baru, $mkg_bulan_baru);                  
    //$stmt->execute(); // execute() is silently error :(
    if (!$stmt->execute()) {
        something_wrong(htmlspecialchars($mysqli->error));
        $mysqli->rollback();
        exit();
    }

    // Get the id_riwayat_gaji from tblriwayatgaji table
    $stmt = $mysqli->prepare($sql_select3);         
    $id = 1;
    $stmt->bind_param("sis", $nip, $id_pegawai, $tmt_baru);
    if (!$stmt->execute()) {
        something_wrong(htmlspecialchars($mysqli->error));
        $mysqli->rollback();
        exit();
    }   
    $result = $stmt->get_result();
    $ds_riwayat = $result->fetch_assoc();
    $id_riwayat_gaji = $ds_riwayat["id_riwayat_gaji"];
    $id_jenis = 'tblriwayatgaji';
    $file_skgb = "sk_gaji_berkala".$id_pegawai."_".$id_riwayat_gaji.".pdf";

    //  Insert data into tbl_pegawai_upload_detail
    $stmt = $mysqli->prepare($sql_insert2);
    $catatan_upload = "TEST1234-".date("Y-m-d H:i:s");
    $stmt->bind_param("isiss", $id_pegawai, $id_jenis, $id_riwayat_gaji, $file_skgb, $catatan_upload);
    //$stmt->execute(); // execute() is silently error :(
    if (!$stmt->execute()) {
        something_wrong(htmlspecialchars($mysqli->error));
        $mysqli->rollback();
        exit();
    }

    $mysqli->commit();

    $path_1 = $path . $nama_file;
    $path_2 = "../../upload/22.sk_gaji_berkala/".$file_skgb."";
    copy($path_1, $path_2);

    success_upload("committed");
}catch(Exception $e){
    $mysqli->rollback();
    something_wrong(throw $e);

}
$stmt->free_result();
$stmt->close();
$mysqli->close();
exit();
/*   END EXCEPTION HANDLER  */

I deliberately put '?' at the last value of $sql_insert1 to test would be the $mysqli->rollback(); called if there was an error in the prepare query.

But it didn't run like what i expected. It run $mysqli->commit() instead.

So i checked my records for all involved tables in process, only "tblriwayatgaji" table that didn't add any data.