Problems Syncing Orders

Just added woocommerce to mailerlite plugin and results not what expected. We have over 5k orders untracked in mailerlite but plugin only has a button saying sync 10 untracked orders? This doesn’t even seem to match no of orders currently awaiting processing which is 13? What does this number mean? How do we sync all existing customers and their order data to mailerlite?

Thanks in advance
Nick

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