ご確認ありがとうございます。
prestigeテーマですと、対応ファイルが違っていまして、スニペットフォルダ内の「buy-buttons.liquid」の中身をまるっと下記のコードと入れ替えてみてください。
{%- comment -%}
----------------------------------------------------------------------------------------------------------------------
BUY BUTTONS
----------------------------------------------------------------------------------------------------------------------
This component is used to show the buy buttons
********************************************
Supported variables
********************************************
* product: the product from which to show the buttons (if empty, a placeholder is displayed)
* show_payment_button: if we show or not the dynamic checkout button
* show_gift_card_recipient: for gift card products, an optional message/email to be sent to the recipient
* atc_button_background: the background of the ATC button
* atc_button_text_color: the color of the ATC button
* payment_button_background: the background of the dynamic payment button
* payment_button_background: the color of the dynamic payment button
* form_id: if specified, define the form ID linked to this input
{%- endcomment -%}
{% if product.tags contains '販売開始日時指定' %}
{% for tag in product.tags %}
{% if tag contains '販売開始日時指定テキスト_' %}
{{ tag | remove:'販売開始日時指定テキスト_' }}
{% endif %}
{% endfor %}
{% else %}
{%- if product != blank -%}
{%- assign variant_picker_block = section.blocks | where: 'type', 'variant_picker' | first -%}
{%- assign recipient_feature_active = false -%}
{%- if product.gift_card? and show_gift_card_recipient -%}
{%- assign recipient_feature_active = true -%}
{%- assign show_payment_button = false -%}
{%- endif -%}
{%- form 'product', product, is: 'product-form', id: form_id -%}
{% liquid
assign button_disabled = false
if product.selected_or_first_available_variant.available == false
assign button_disabled = true
assign button_content = 'product.general.sold_out_button' | t
else
if product.template_suffix contains 'pre-order'
assign button_content = 'product.general.pre_order_button' | t
else
assign button_content = 'product.general.add_to_cart_button' | t
endif
endif
%}
{%- if recipient_feature_active -%}
{%- endif -%}
{%- endform -%}
{%- else -%}
{%- endif -%}
{% endif %}