If the keys are empty, the easiest way is to download this page https://iancoleman.io/bip39/. You can run it locally (without internet access). Put your seed, enter BIP49 derivation and locate your address. Take the key and import it into Core. Core should recognize it. It's better to do it on a newly generated wallet (to make the next step easier)

Then, things start to get interesting. Core does not know that it is a segwit key. You have to generate redeeming script for the witness with addwitnessaddress command. But you have to know the key hash of the public key. There are tools avaiable for that but probably the easiest would be to export the wallet to a text file dumpwallet "filename" from Core console. Read the file and locate the address (you will recognize by the private key). Then return to console and do addwitnessaddress address. That is still not enough. You have to rescan the wallet. Exit Core and run it with -rescan option.