Shipments missing apartment number?- failed delivery

I ordered something on AliExpress from Poland to the Netherlands and it couldn't be delivered by DHL, as the seller hadn't put my apartment number extension (after the house number) on it.

Has anyone else been having this issue? I also had two other failed deliveries prior from Polish warehouses, and I think they might have had the same problem; I hadn't checked with DHL on those though.

The seller sent me a screenshot of the delivery data as it appears on their end and the apartment extension wasn't displayed in it. It is however visible to me when I check my shipping address, entered in the box next to the building number.

What do you all think is going on?