Custom comment field not showing when logged-in

I’m not sure I fully understand your question, but to add some HTML (just over or under the submit field) that is visible to both logged-in and logged-out users, you can try the following:

add_filter( 'comment_form_submit_field', function( $submit_field )
{
    //-----------------------------------
    // Adjust the prepend to your needs
    //-----------------------------------
    $prepend = '<p> Prepend some HTML </p>';

    //-----------------------------------
    // Adjust the append to your needs
    //-----------------------------------
    $append = '<p> Append some HTML </p>';

    return $prepend . $submit_field . $append;
} );

Other workarounds are possible, like the comment_form action.

There are some comment-form filters that are only available to logged-out users, like the

• comment_form_before_fields
• comment_form_field_{$name}
• comment_form_after_fields

So most likely you’re trying to hook into those filters – but you haven’t mentioned what filters you’re using.