Method 1
Open the debug console and enter the following commands:
restoreaddresses 100 rescanblockchain
If your address is still missing please check this more detailed guide: https://veil.freshdesk.com/support/solutions/articles/43000472093-how-to-correctly-restore-wallet-from-seed-words-or-find-lost-veil
Method 2
1. Find the address you are missing and copy the address.
2. Open the debug console and enter the following command:
getaddressinfo <address>
3. Find the line ismine and it should say true, if it says false you might have restored from an incorrect seed or copied an incorrect address. If ismine : true go to step 4
4. Input commands:
dumpprivkey <address> importprivkey <outputfromdumpprivkey> <oldaddress>
All commands should be without the < >