They were probably sent to another change address in your wallet. Activate coincontrol in bitcore qt. And check to wich address the money went. Then you can send them to your registered adress or register the new address too.
https://bitcore.cc/Bitcore_CoinControl.pdfWow thank you, looks promising in my wallet. It looks like it really went to a wallet called "(Wechselgeld)" (change money in engl.). Can I now simply send it from this change address to my airdrop registered wallet and receive the full airdrop amount?
Yeah you can and should send it back to your registered airdrop address, this way you make sure to get the airdrop properly next time.