last_value different result from mv and ad hoc query

[st1page]

create table t1(
    id bigint primary key,
    uid bigint,
    value bigint,
    ts bigint
);
insert into t1 values(1, 1, null, 1),(2, 1, 2, 2),(3, 1, 3, 3);
flush;
select
    uid,
    last_value(case when ts=2 then value else null end order by ts) as lv
from t1
group by uid;
 uid | lv
-----+----
   1 |  2
(1 row)
create materialized view mv1 as
select
    uid,
    last_value(case when ts=2 then value else null end order by ts) as lv
from t1
group by uid;
select * from mv1;
 uid | lv
-----+----
   1 |
(1 row)