When you sync with Amazon you can only sync with your own Seller Central Account (check and you should see this is definitely in sync after allowing time for Amazon to process). 

What Amazon decides to show on the ‘front end’ i.e. the public facing product page is entirely at their discretion.  This is usually because multiple sellers are sending multiple different images, titles, descriptions etc. for the same product.  Even if you are selling a product unique to you, Amazon may not decide to update the front end listing.  Usually it does after a day or so but not always.  You can try contacting Amazon support in these cases.

Remember also that what Amazon by Codisto syncs with Amazon Seller Central is affected by the configuration settings you choose so if for example you have configured a product to have a different price on Amazon to that in Shopify (either using a fixed price, a pricing operator or an attribute mapped custom Amazon field price) then this could be a reason why your Shopify product doesn't reflect what's in Seller Central.

If you believe there is in fact a sync problem, please reach out to ascsupport@codisto.com.