Different results of selects from view and CTE with same definition

MariaDB [test]> CREATE VIEW v AS

    -> SELECT

    ->   (SELECT SUM(t4.b) FROM t1, t2 WHERE t1.a = t2.b GROUP BY t1.a) AS m

    -> FROM t3, t4

    ->   WHERE t3.a = t4.b;

Query OK, 0 rows affected (0.004 sec)

MariaDB [test]> SELECT * FROM v;

+------+

| m    |

+------+

|    2 |

|    7 |

+------+

2 rows in set (0.001 sec)

MariaDB [test]> WITH cte AS (

    -> SELECT

    ->   (SELECT SUM(t4.b) FROM t1, t2 WHERE t1.a = t2.b GROUP BY t1.a) AS m

    -> FROM t3, t4

    ->   WHERE t3.a = t4.b

    -> )

    -> SELECT * FROM cte;

+------+

| m    |

+------+

|    9 |

+------+

1 row in set (0.001 sec)

CREATE TABLE t1 (a INT PRIMARY KEY, b INT) ENGINE=MyISAM;

INSERT INTO t1 VALUES (1,1), (2,2);

CREATE TABLE t2 (a INT PRIMARY KEY, b INT) ENGINE=MyISAM;

INSERT INTO t2 VALUES (1,1), (3,3);

CREATE TABLE t3 (a INT PRIMARY KEY, b INT) ENGINE=MyISAM;

INSERT INTO t3 VALUES (2,2), (4,4), (7,7);

CREATE TABLE t4 (a INT PRIMARY KEY, b INT) ENGINE=MyISAM;

INSERT INTO t4 VALUES (2,2), (5,5), (7,7);

CREATE VIEW v AS

SELECT

  (SELECT SUM(t4.b) FROM t1, t2 WHERE t1.a = t2.b GROUP BY t1.a) AS m

FROM t3, t4

  WHERE t3.a = t4.b;

SELECT * FROM v;

WITH cte AS (

SELECT

  (SELECT SUM(t4.b) FROM t1, t2 WHERE t1.a = t2.b GROUP BY t1.a) AS m

FROM t3, t4

  WHERE t3.a = t4.b

)

SELECT * FROM cte;

DROP VIEW v;

DROP TABLE t1,t2,t3,t4;

MariaDB [test]> SELECT

    ->   (SELECT SUM(t4.b) FROM t1, t2 WHERE t1.a = t2.b GROUP BY t1.a) AS m

    -> FROM t3, t4

    ->   WHERE t3.a = t4.b;

+------+

| m    |

+------+

|    9 |

+------+