onyatchi1, try the next algo: 1. copy your v2 wallet.dat to v3 work folder. 2. Run v3 wallet and open console. 3. Write: dumpwallet "keys". Wait until it finish. 4. Exit from wallet. 5. Remove wallet.dat from v3 folder and run v3 wallet again. 6. In console write: importwallet "keys". 7. Say thanks to danbi if it helps .
As I understand you have another dmd address in your v2 wallet.dat (not only dNXQdyhKBTzU2X61pDVoHnr4qzmj8G2Bwm). And when you migrate to v3 this address lost in some reason. But it still present at old wallet.dat. And you need import all private keys correctly.