made a couple minor changes to your code
<?php
// check if the flexible content field has rows of data
if( have_rows('flexible_content') ):
// loop through the rows of data
while ( have_rows('flexible_content') ) : the_row();
if( get_row_layout() == 'social_proof_logos' ):
$field = get_sub_field_object('social_proof');
$choices = $field['choices'];
$value = the_sub_field('social_proof');
if( $value ) :
echo '<ul>';
foreach( $value as $v ):
echo '<li>';
echo $choices[ $v ];
echo '</li>';
endforeach;
echo '</ul>';
endif;
endif;
endwhile;
else :
// no layouts found
endif;
// End
?>
