My shopify site keeps changing size selected by customer to Base Variant Size XS

[YC3]

Hello,

I am facing an issue whereby a customer ads clothing items on www.yogacrow.com to their cart with a size they selected and at some point - either when it is added to the cart or after the purchase is processed - the site seems to be changing the size variant to whatever the base size variant is (XS, PETITE, ETC) rather than what the customer selected/ordered. 

I am unable to recreate this issue on demand yet it is happening a lot - one expert who researched it for me provided the below information which seems a viable cause yet I need help to fix the issue:

ANY HELP WOULD BE GREATLY APPRECIATED as this is causing a logistical headache with lots of returns etc.

With gratitude

[BSS-Commerce]

Hi @YC3 ,

We've carefully checked your website and found your problem quite complicated. So we suggest hiring a developer.

It's what we can help with an optimal solution. If you need help from our expert, kindly share your request with us via Shopify experts: https://experts.shopify.com/bss-commerce/services?utm_source=Shopify+Community&utm_medium=Post+reply...

We will check it and give you a detailed solution. We're looking forward to working with you.