Open fulfillments turned into cancelled

Shopify Partner
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Normally, when the order is created, the fulfillments is empty. However, we just saw a case that when the order was created, the fulfillments was already provided an “open” status. When we created a new fulfillment later, the status turned “cancelled”, and we are not able to fulfill it anymore. Not sure if it’s caused by a third party order creating app or anything, has anyone seen this case before? How can we resolve it?