draftOrderComplete is broken (Both Graphql and REST)

[Roy1985]

I have created an app to create orders and it looks like something has been broken since last week...

Here is my problem. I use draftOrderCreate to create a draft order for customer X. After it's done, I checked Shopify Admin and everything looks fine. However when I use draftOrderComplete to complete that order, the customer of the completed order will have a 50 / 50 chance to change to customer Y.

Is there anyone else facing the same problem as mine? This is super frustrating as it all happens by chance and there is no way for me to figure out the root cause.

[gfernandez]

also, there is a not documented flag 

paymentPending: boolean