NULLIF function returns -32768 instead of NULL when querying a Columnstore table

create schema if not exists Z213035;

use Z213035;

CREATE TABLE `CS_LEG` (`ID` bigint(20) DEFAULT NULL, `sess_count` smallint(6) DEFAULT NULL) ENGINE=Columnstore;

CREATE TABLE `INNO_LEG` (`ID` bigint(20) DEFAULT NULL, `sess_count` smallint(6) DEFAULT NULL) ENGINE=InnoDB;

insert into CS_LEG(ID) values(1);

insert into INNO_LEG(ID) values(1);

select NULLIF(sess_count,0) from CS_LEG;

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

| NULLIF(sess_count,0) |

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

|               -32768 |

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

select NULLIF(sess_count,0) from INNO_LEG;

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

| NULLIF(sess_count,0) |

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

|                 NULL |

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