Composite index with count scan returns wrong results

A simple test repro gives wrong results:

insert into default values("k01",

{"f1":1, "f2":true}

);
insert into default values("k02",

{"f1":2, "f2":false}

);
insert into default values("k03",

{"f1":3, "f2":true}

);
insert into default values("k04",

{"f1":4, "f2":false}

);
insert into default values("k05",

{"f1":5, "f2":true}

);
create index ix1 on default(f1,f2);

select count(1) from default where f1 < 3 and f2 = true;
Above query returns 2 rows.
Also
select count from default where f1 < 3 and f2 = true;
returns 2 rows.
Because both use count scan.

But
select count(f1) from default where f1 < 3 and f2 = true;
returns 1 row because it doesnt use the count scan.

Please try other combinations.
Also uploading the test case which failed for rqg.