If the database is Oracle, the name of the feeds are not displayed if they are haven't preferredtitle. With Oracle, a space (' ') is stored in preferredtitle instead of empty string (''). Thats why the following SQL sentence in /blocks/rss_client/edit_form.php file is not working for us:

{{
$titlesql = "CASE WHEN preferredtitle = '' THEN {$DB->sql_compare_text('title', 64)} ELSE preferredtitle END";
}}

To make it work with any database it would be necessary to replace the previous line with the following:

{{
$titlesql = "CASE WHEN preferredtitle = '' OR TRIM(preferredtitle) IS NULL THEN {$DB->sql_compare_text('title', 64)} ELSE preferredtitle END";
}}

With ORACLE the behaviour of TRIM is different from MySQL and returns NULL instead ''. So its necessary to mantein the current check and to add the correct one for Oracle to make code compatible with any database system.