pg_dump of partitioned table not working.

What am I missing?

(Specifying the whole file name because multiple versions are installed.)

$ /usr/lib/postgresql/12/bin/pg_dump --version
pg_dump (PostgreSQL) 12.5 (Ubuntu 12.5-1.pgdg18.04+1)

postgres=# \d+ measurement
                            Partitioned table "public.measurement"
   Column   |  Type   | Collation | Nullable | Default | Storage | Stats 
target | Description
-----------+---------+-----------+----------+---------+---------+--------------+-------------
  city_id   | integer |           | not null |         | plain   
|              |
  logdate   | date    |           | not null |         | plain   
|              |
  peaktemp  | integer |           |          |         | plain   
|              |
  unitsales | integer |           |          |         | plain   
|              |
Partition key: RANGE (logdate)
Indexes:
     "measurement_pkey" PRIMARY KEY, btree (city_id, logdate)
Partitions: measurement_y2019h1 FOR VALUES FROM ('2019-01-01') TO 
('2019-07-01'),
             measurement_y2019h2 FOR VALUES FROM ('2019-07-01') TO 
('2020-01-01'),
             measurement_y2020h1 FOR VALUES FROM ('2020-01-01') TO 
('2020-07-01'),
             measurement_y2020h2 FOR VALUES FROM ('2020-07-01') TO 
('2021-01-01')

postgres=# select * from measurement;
  city_id |  logdate   | peaktemp | unitsales
---------+------------+----------+-----------
        5 | 2019-05-03 |          |
        5 | 2020-11-22 |       77 |        45
        4 | 2020-11-22 |       77 |        45
(3 rows)

$ /usr/lib/postgresql/12/bin/pg_dump -p5433 -d postgres -t measurement 
--data-only
--
-- PostgreSQL database dump
--

-- Dumped from database version 12.5 (Ubuntu 12.5-1.pgdg18.04+1)
-- Dumped by pg_dump version 12.5 (Ubuntu 12.5-1.pgdg18.04+1)

SET statement_timeout = 0;
SET lock_timeout = 0;
SET idle_in_transaction_session_timeout = 0;
SET client_encoding = 'UTF8';
SET standard_conforming_strings = on;
SELECT pg_catalog.set_config('search_path', '', false);
SET check_function_bodies = false;
SET xmloption = content;
SET client_min_messages = warning;
SET row_security = off;

--
-- PostgreSQL database dump complete
--



-- 
Angular momentum makes the world go 'round.