Shamim's Plugins

Please add following code in your theme’s (child theme’s if you are using) functions.php

add_filter('fep_directory_table_columns', function( $columns ){
    unset($columns['name']);
    return $columns;
});

instead of $user = wp_get_current_user(); use $user = get_userdata( $userid );

Are you logged in as same user as that admin? You cannot send message to yourself.
Log in as another user and try again.

Let me know.

Can you please give me your website url so that i can try?

How many total messages you have?
You can find all messages in DB table named PREFIX_fep_messages where PREFIX is your DB table prefix.

Is it slow when sending messages or reading messages as well?
How big is your website is? Do your use any object caching? Eg. memcached?

This can be done easily, but you need some knowledge in php as we need to modify template.
You can find instruction in https://www.shamimsplugins.com/docs/front-end-pm-pro/customization-front-end-pm-pro/change-templates/

1. To remove count in header section you will need to edit header.php
2. To remove search field you will need to edit box-message.php
3. To remove participants and title you will need to edit view-message-content.php

1. Did you added following code?

add_filter( 'fep_page_id_filter', function( $page_id ){
    if( $page_id && function_exists( 'pll_get_post' ) ){
        $page_id = pll_get_post( $page_id );
    }
    return $page_id;
});

2. Can you please keep that page public then clear all cache then try?
3. If still not working you can set Front End PM Page to your Finnish one then try.

Let me know.