Why ELSEIF is not reached?

Question

I have prepared an before update trigger in which I have encoded hierarchical relation:

CREATE DEFINER=`%`@`%` TRIGGER setToClosed
    BEFORE UPDATE ON issues
    FOR EACH ROW 
BEGIN
    declare project_id1 int;
    set @project_id1 = (select id from projects where name = 'XXX');
    IF (new.done_ratio=100) THEN
        IF (new.project_id =  @project_id1) THEN
            SET new.status_id=4;
        ELSEIF new.project_id in (
                        select  id
                        from    (select * from projects) projects_sorted,
                                (select @pv := @project_id1) initialisation
                        where   find_in_set(parent_id, @pv) > 0
                        and     @pv := concat(@pv, ',', id)) THEN
            SET new.status_id=4;

        ELSE
            SET new.status_id=5;
        END IF;
    END IF;

END

I would like to ask why ELSEIF is not reached? I have tested a standalone query from ELSEIF ant it returns list of ids.

After changes in row which status_id is present in ELSEIF query a trigger enters to ELSE.

How should I proceed ?