Your order was cancelled on Etsy, but Shopify would not cancel the matching Shopify order because the order has a return.
Why it happens
Shopify does not cancel an order that has a return. It makes no difference whether the return is still open or already finished. Open the order in Shopify and check which of these applies:
The order has an open return. A return was started on the order and has not been closed yet.
The order has a completed return. Closing the return does not help, because Shopify still will not cancel the order.
Shuttle never creates, changes or closes returns, so it cannot clear this for you. The Shopify order stays open until you close it yourself.
How to fix it
In your Shopify admin, go to Orders and open the order.
Find the return on the order. If it is still open, finish it, and restock any items that came back to you.
Use Refund on the order to refund what is left on it, so it matches the cancelled Etsy order. Do not try to cancel the order, because Shopify will not cancel it while it has a return.
If there is nothing left to refund, archive the order in Shopify.
Still seeing it?
Contact support if you cannot find a return on the order in Shopify, or if Shopify will not let you refund the order after the return is resolved.