For words that only have three letters, there is absolutely no 4th letter. One example is with the word “increase”, there won't be any far more letters Later on and thus should be the word "increase". The word “addict” is within the BIP39 wordlist however , you would've employed “addi” https://socialupme.com/story5172129/the-5-second-trick-for-ledger-seed-phrase-bip39