The latest version of pgAdmin 4.4 does not allow you to select a table and look at the DDL. You get the following error message:
<snipped>
Perhaps PgAdmin 4.4 does not support the version of Postgres you are querying? PgAdmin 4.4 works for me against Postgres 11.2.
The PgAdmin support email list is actually "pgadmin-support", and can be found at https://www.pgadmin.org/support/list/; you might be better off contacting the PgAdmin team there.