PayPal declined the dispute for a reason that is a condition of creating such a dispute

[ViacheslavK]

My dispute case (the 1 item (weight 650g) from 3 ordered was not delivered inside parcel (weight 234g)).

So my dispute case form is:

So PayPal dispute decision is: "We are denying your case. This decision was made because we received shipment tracking from the merchant confirming that the merchandise was delivered."

But, This dispute case by itself says: it is exist some delivered track number for other received items. So, by definition, it was impossible to decline this dispute by reason of existence of delivered track even in the case if I hadn't written a single word in that dispute (as such track number is a condition to create such dispute case)! 

To be clear, this dispute was closed 40 days after just because this dispute form was filled.

Community, please help! How is it possible? How to solve it?