Four Season Products review for Google & YouTube

I have been using Google Merchant Centre linked to my Shopify store for years and, until recently, it worked ok (with the odd glitch). More recently, however, all my products have expired for no reason, the product pages show that Google feed is not linked with an error message of "Add shipping cost for your product" (even though my shipping options have not changed) and I cannot even link to my existing GMC account through the app. This is not good enough.