Query planner not using Index scan for WHERE IN condition [duplicate]

Question

I have a table INVENTORY in PGv9.6.11 and when a run query with WHERE _column_ IN(), query planner using seq scan even have index on that _column_

CREATE TABLE INVENTORY
(
    process_id bigint,
    load_dttm timestamp(6) without time zone,
    md5_checksum character varying(200)  ,
    storeid character varying(200),
    inventorystatus character varying(200),
    inventorytype character varying(200),
    materialdescription character varying(200),
    serial_nbr character varying(200) ,
    activityid character varying(200) ,
    channel character varying(200) ,
    lastupdateddate timestamp(6) without time zone,
    src_file_date timestamp(6) without time zone,
    run_id character varying(40) "
)

I have created indexes in a different ways but none of them are using query planner ,

Reguler Index:

Create index idx_test1 on INVENTORY (inventorystatus)

partial Index:

Create index idx_test2 on INVENTORY (inventorystatus) where inventorystatus = ANY ('{Received,Returned}')

and 

Create index idx_test3 on INVENTORY (inventorystatus) where inventorystatus in ('Received','Returned')

When I run explain analyze on the user query:

EXPLAIN ANALYZE select * from  INVENTORY
where INVENTORYSTATUS in ('Received','Returned')

And Query planner is:

Seq Scan on inventory  as inventory (cost=0..121384.49 rows=2603713 width=157)
Filter: ((inventory.inventorystatus)::text = ANY ('{Received,Returned}'::text[]))

Not sure what I'm missing here, any suggestions?