It looks like the function requires an ID so using your code you would just do
<?php
$field = get_field('header-work');
$image = $field['image']; //acf-image-field is set to return id
?>
<section>
<div class="image">
<img class="img-fluid" <?php awesome_acf_responsive_image($image,'thumb-640','2560px'); ?>>
</div>
</section>
If that does not work then you should ask the developer of the plugin.