Using Drupal 8.6.15 with Php 7.2. This issue I have checked with a fresh drupal installation no other theme, only with Bartik.
I have created a product attribute called Tiles Color. It suppose to display in the add-to-cart form. But its not displaying there. What I did, I have created a new product type "pack" along with new product variation type "pack" and attach the new product variation to a new order item type called "Pack Item". See the image "attribute-image-with-pack-item.jpg".
When I attach new product variation type "pack" with new order item "pack Item", in the add-to-cart section, it shows variation autocomplete and quantity and NO attribute dropdown. But if I attach it with Default Order Item type, it shows the attribute dropdown and no variation autocomplete textbox, which is the correct display I want to achieve. See "attribute-image-with-default.jpg".
But in the actual live site, where I was facing the issue, I switched to Bartik theme, whatever I attach to pack order item or default order item, it always shows the variation dropdown, no way I am getting the attribute dropdown. I have deleted all new types and attributes, but result is same. see image "attribute-image-with-any-item.jpg".
Is this a bug or am I missing anything? Can anyone help me out?