When were they sent? They will be marked as complete automatically if you don't mark them as received or open a dispute.
That's the strange thing, the purchase protection is still running and the order itself is still open, and I can confirm receipt still. It's only the tracking details that have changed to completed. That includes items sent 2 months ago as well as 3 weeks ago, all were showing as a mix of awaiting airline, arrived in destination country or with last mile carrier. Some still have 50+ days of purchase protection as they were extended.
The ones that purchase protection expired on earlier in the week, I was able to open a dispute on and they were refunded as the seller wouldn't respond to a request to extend the protection.