LDI followed by INSERT SELECT statements with cpimport disabled returns incorrect results

MariaDB [dml]> set columnstore_use_import_for_batchinsert=off;

Query OK, 0 rows affected (0.000 sec)

MariaDB [dml]> DROP TABLE IF EXISTS cache1;

Query OK, 0 rows affected (0.360 sec)

MariaDB [dml]> CREATE TABLE cache1 (a int, b varchar(44))engine=columnstore;

Query OK, 0 rows affected (0.475 sec)

MariaDB [dml]> \! rm -f /tmp/columnstore_cache_data.txt

MariaDB [dml]> SELECT l_orderkey, l_comment FROM lineitem LIMIT 501 INTO OUTFILE '/tmp/columnstore_cache_data.txt' FIELDS TERMINATED BY ',' ENCLOSED BY '"';

Query OK, 501 rows affected, 1 warning (0.232 sec)

MariaDB [dml]> LOAD DATA LOCAL INFILE '/tmp/columnstore_cache_data.txt' INTO TABLE cache1 FIELDS TERMINATED BY ',' ENCLOSED BY '"';

Query OK, 501 rows affected (0.236 sec)              

Records: 501  Deleted: 0  Skipped: 0  Warnings: 0

MariaDB [dml]> SELECT COUNT(*) FROM cache1;

+----------+

| COUNT(*) |

+----------+

|      501 |

+----------+

1 row in set (0.042 sec)

MariaDB [dml]> DELETE FROM cache1;

Query OK, 501 rows affected (0.158 sec)

MariaDB [dml]> DROP TABLE IF EXISTS cache_inno1;

Query OK, 0 rows affected (0.012 sec)

MariaDB [dml]> CREATE TABLE cache_inno1 (a int, b varchar(44));

Query OK, 0 rows affected (0.015 sec)

MariaDB [dml]> INSERT INTO cache_inno1 VALUES (1, 'a'), (2, 'b');

Query OK, 2 rows affected (0.003 sec)

Records: 2  Duplicates: 0  Warnings: 0

MariaDB [dml]> INSERT INTO cache1 SELECT * FROM cache_inno1;

Query OK, 2 rows affected (0.174 sec)

Records: 2  Duplicates: 0  Warnings: 0

MariaDB [dml]> INSERT INTO cache1 SELECT * FROM cache1;

Query OK, 2 rows affected (0.221 sec)

Records: 2  Duplicates: 0  Warnings: 0

MariaDB [dml]> SELECT * FROM cache1;

+------+----------+

| a    | b        |

+------+----------+

|    1 | a        |

|    2 | b        |

|    1 | _CpNoTf_ |

|    2 | _CpNoTf_ |

+------+----------+

4 rows in set (0.015 sec)

MariaDB [dml]> INSERT INTO cache1 SELECT * FROM cache1;

Query OK, 4 rows affected (0.192 sec)

Records: 4  Duplicates: 0  Warnings: 0

MariaDB [dml]> SELECT * FROM cache1;

+------+----------+

| a    | b        |

+------+----------+

|    1 | a        |

|    2 | b        |

|    1 | _CpNoTf_ |

|    2 | _CpNoTf_ |

|    1 | NULL     |

|    2 | NULL     |

|    1 | NULL     |

|    2 | NULL     |

+------+----------+

8 rows in set (0.016 sec)