To add a little more information I believe it has to do with my code here:
product-grid-collage.liquid
{% assign collection_index__product = forloop.index %}
{% assign remaining_length__product = collection_product_count__product | minus: collection_index__product %}
{% comment %}
If there are more than three items left we want to put them in a 3
or reverse 3 row
3 row = 1 large product on the left, 2 small on the right
reverse 3 row = 2 small products on the left, 1 large on the right
{% endcomment %}
{% if remaining_length__product > 3 %}
{% assign is_three_row__product = true %}
{% endif %}
{% comment %}
Put remaining items in a 2 row if necessary.
{% endcomment %}
{% if remaining_length__product < 4 and three_row_index__product > 2 %}
{% assign is_three_row__product = false %}
{% endif %}
{% comment %}
If the total number of products is divisible by 3, we will just use
3 and reversed 3 item rows
{% endcomment %}
{% if divisible_by_three__product == 0 %}
{% assign is_three_row__product = true %}
{% endif %}
{% comment %}
If we set is_three_row__product to true based on the conditionals above.
{% endcomment %}
{% if is_three_row__product == true %}
{% if three_row_index__product > 2 %}
{% if is_reverse_row__product %}
{% assign is_reverse_row__product = false %}
{% else %}
{% assign is_reverse_row__product = true %}
{% endif %}
{% assign three_row_index__product = 0 %}
{% endif %}
{% comment %}
Assign grid classes for 3 rows and reverse 3 rows
{% endcomment %}
{% case three_row_index__product %}
{% when 0 %}
{% if is_reverse_row__product %}
{%- assign width = 270 -%}
{%- assign height = 190 -%}
{% assign grid_item_width = 'grid__item--small one-whole reverse' %}
{% else %}
{%- assign width = 650 -%}
{%- assign height = 480 -%}
{% assign grid_item_width = 'grid__item--large one-whole medium--two-thirds large--two-thirds' %}
{% endif %}
{% when 1 %}
{% if is_reverse_row__product %}
{%- assign width = 270 -%}
{%- assign height = 190 -%}
{% assign grid_item_width = 'grid__item--small one-whole reverse' %}
{% else %}
{%- assign width = 270 -%}
{%- assign height = 190 -%}
{% assign grid_item_width = 'grid__item--small one-whole medium--one-third large--one-third' %}
{% endif %}
{% when 2 %}
{% if is_reverse_row__product %}
{%- assign width = 650 -%}
{%- assign height = 480 -%}
{% assign grid_item_width = 'grid__item--large one-whole medium--two-thirds large--two-thirds reverse clearfix' %}
{% else %}
{%- assign width = 270 -%}
{%- assign height = 190 -%}
{% assign grid_item_width = 'grid__item--small one-whole medium--one-third large--one-third clearfix' %}
{% endif %}
{% endcase %}
{% if three_row_index__product == 0 %}
<div class="grid__item collage-grid__row">
<div class="grid">
{% endif %}
{% comment %}
Wrap one-third items in reversed groups, so they can be floated properly without changing the order of products in the grid.
{% endcomment %}
{% if is_reverse_row__product and three_row_index__product == 0 %}
<div class="grid__item collage-grid__reverse--wrapper one-whole medium--one-third large--one-third">
<div class="grid">
{% endif %}
{% comment %}Product Grid Item{% endcomment %}
{% include 'product-grid-item' %}
{% comment %}
Close out wrapper div for one-third reverse items
{% endcomment %}
{% if is_reverse_row__product and three_row_index__product == 1 %}
</div>
</div>
{% endif %}
{% if three_row_index__product == 2 %}
</div>
</div>
<div class="grid__row-separator"></div>
{% endif %}
{% comment %}
Increment the group of three counter
{% endcomment %}
{% if three_row_index__product <= 2 %}
{% assign three_row_index__product = three_row_index__product | plus: 1 %}
{% endif %}
{% continue %}
{% endif %}
{% if collection_product_count__product == 1 %}
{% comment %} Set full width when there is 1 product in a collection by making
`grid_item_width` an empty string {% endcomment %}
{% assign grid_item_width = '' %}
{%- assign image_size = 'max' -%}
{%- assign width = 100% -%}
{%- assign height = 630 -%}
{% include 'product-grid-item' %}
{% break %}
{% else %}
{% comment %} Set item with to half if it isn't in a 3 row. {% endcomment %}
{% assign grid_item_width = 'one-whole medium--one-half large--one-half' %}
{%- assign image_size = 'max' -%}
{%- assign width = 100% -%}
{%- assign height = 270 -%}
{% include 'product-grid-item' %}
{% comment %}add grid row separator between the last two rows{% endcomment %}
{% if remaining_length__product == 2 %}
<div class="grid__row-separator"></div>
{% endif %}
{% comment %} We still need to increment the three_row_index_product {% endcomment %}
{% if three_row_index__product <= 2 %}
{% assign three_row_index__product = three_row_index__product | plus: 1 %}
{% endif %}
{% endif %}
