You could try resynching the integration. Other option which might be easier, is to just export the customer data from Shopify and manually import it into the correct klaviyo list. 

Hi Akers Digital, Thank your from your reply.

I tried resynching the integration. But Did not work.

I want to know, In default when we integration our Klaviyo with a Shopify which already had some customers !   automatically sync our customers from Shopify into Klaviyo list without manually or not ? 

Hi @Ferdouus_Kazemi,

When you integrate Klaviyo with Shopify, by default the integration will automatically sync your existing customers from Shopify into Klaviyo. You will not need to manually add them. This is done using the Klaviyo-Shopify connector, which can be installed from the Shopify App Store.

Keep in mind that Klaviyo can only sync customer data for customers who have consented to receive email communications from you.

Hey @Ferdouus_Kazemi,

In case you missed the callout in our Getting started with Shopify Help Center article:

Klaviyo will not automatically sync historical subscribers to a list when a customer checks Subscribe new customers to a Klaviyo list. If you need to add historical subscribers to your newsletter list, you can do so with property and flow editing as outlined in How to add or combine lists without triggering a flow. You can also add subscribers to a list manually by following How to add subscribers to an existing list. 

As it explains, to @mauromorero’s point, your customers from Shopify will be synced over (as profiles), but they won’t be added to a Klaviyo list automatically. 

For this reason, like what @Akers Digital suggested manually exporting your Shopify list and importing them into your desired Klaviyo list would be easiest.

David