Error when using OR in case THEN portion

create database ct;
use ct;
create table test_inno (astr VARCHAR(50))ENGINE = INNODB ;
create table test_mcs (astr VARCHAR(50))ENGINE = COLUMNSTORE ;
INSERT INTO test_inno (astr) value('test');
INSERT INTO test_mcs (astr) value('test');

innodb:
SELECT astr FROM test_inno WHERE CASE WHEN 1 = 1 THEN (astr = 'test' OR astr = 'unknown') END;
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1 row in set (0.01 sec)

columnstore:
SELECT astr FROM test_mcs WHERE CASE WHEN 1 = 1 THEN (astr = 'test' OR astr = 'unknown') END;
ERROR 1178 (42000): The storage engine for the table doesn't support Unknown item type