Visually hidden setting for label does not seem to have any effect

The Display Suite field templates don't add a visually-hidden class but a field-label-visually-hidden class. Therefore the CSS that hides the element doesn't get applied.

.visually-hidden {
  position: absolute !important;
  clip: rect(1px, 1px, 1px, 1px);
  overflow: hidden;
  height: 1px;
  width: 1px;
  word-wrap: normal;
}

As an example the part from ds-field.reset.html.twig responsible for this:

{% if not label_hidden %}
  <div class="field-label-{{ element['#label_display']|clean_class }}">
    {{- label }}{% if show_colon %}:{% endif -%}
  </div>
{% endif %}

Still occurs with Display Suite 8.x-3.2
The bug also occurs with the expert and minimal templates, not only the reset template.

Should we add 'visually-hidden' to 'field-label-visually-hidden' to be backwards compatible?
But then still FieldTemplateTest will probably need some adjustments to keep working.

Should we add 'visually-hidden' to 'field-label-visually-hidden' to be backwards compatible?

Yes please! The issue persists in Drupal 8.8 with Display Suite 8.x-3 - and its really confusing.

Inspired by a related issue #2779743: Hidden/Visually hidden field labels don't work in the basic theme and for a quick fix - I've modified the following lines in ds-field-expert.html.twig

  set title_classes = [
        'field-label-' ~ element['#label_display']|clean_class,
      ]

So they now read:

  set title_classes = [
        'field-label-' ~ element['#label_display']|clean_class,
        (element['#label_display'] == 'visually_hidden' ? 'visually-hidden'),
      ]

Hmm, yeah, this is confusing indeed.

We should apply this to expert, minimal and (even) reset, let me see if I can make it work.

This also adds visually hidden to the labels of display suite fields.

Patch didn't apply anymore, will commit when green.

committed and pushed, sorry for the delay.