Ajax cart stopped working on Venture theme

[Matty3]

I have venture theme installed, but after a few modifications, the option to add products to the cart without leaving the product page has stopped working. Even though it is selected in the theme customisation. 

Here is a copy of the form code from the product pages, as I guess this may be where the problem lies:

        <form action="/cart/add" method="post" enctype="multipart/form-data" class="product-form" id="AddToCartForm-{{ section.id }}">

          {% unless product.options.size == 1 and product.variants[0].title == 'Default Title' %}
            {% for option in product.options_with_values %}
              <div class="selector-wrapper js product-form__item">
                <label {% if option.name == 'default' %}class="label--hidden" {% endif %}for="SingleOptionSelector-{{ section.id }}-{{ forloop.index0 }}">{{ option.name }}</label>
                <select class="single-option-selector single-option-selector-{{ section.id }} product-form__input"
                  id="SingleOptionSelector-{{ forloop.index0 }}"
                  data-name="{{ option.name }}"
                  data-index="option{{ forloop.index }}">
                  {% for value in option.values %}
                    <option value="{{ value | escape }}"{% if option.selected_value == value %} selected="selected"{% endif %}>{{ value }}</option>
                  {% endfor %}
                </select>
              </div>
            {% endfor %}
          {% endunless %}

          <select name="id" id="ProductSelect-{{ section.id }}" class="product-form__variants no-js">
            {% for variant in product.variants %}
              <option {% if variant == current_variant %} selected="selected" {% endif %} data-sku="{{ variant.sku }}" value="{{ variant.id }}" {% unless variant.available %} disabled="disabled" {% endunless %}>
                {% if variant.available %}
                  {{ variant.title }} - {{ variant.price | money_with_currency }}
                {% else %}
                  {{ variant.title }} - {{ 'products.product.sold_out' | t }}
                {% endif %}
              </option>
            {% endfor %}
          </select>
          
          <div class="product-form__item product-form__item--quantity">
            <label for="Quantity">{{ 'products.product.quantity' | t }}</label>
            <input type="number" id="Quantity" name="quantity" value="1" min="1" class="product-form__input product-form__quantity">
          </div>
          
          <div class="product-form__item product-form__item--submit">
            <button type="submit"
              name="add"
              id="AddToCart-{{ section.id }}"
              class="btn btn--full product-form__cart-submit{% unless current_variant.available %} btn--sold-out{% endunless %}"
              {% unless current_variant.available %}disabled="disabled"{% endunless %}>
              <span id="AddToCartText-{{ section.id }}">
                {% unless current_variant.available %}
                  {{ 'products.product.sold_out' | t }}
                {% else %}
                  {{ 'products.product.add_to_cart' | t }}
                {% endunless %}
              </span>
            </button>
          </div>
          
        </form>

Could anybody help?