For words that have only three letters, there's no 4th letter. One example is with the word “increase”, there aren't any far more letters Later on and thus needs to be the word "insert". The word “addict” is within the BIP39 wordlist however , you might have used “addi” for https://letsbookmarkit.com/story18866949/how-much-you-need-to-expect-you-ll-pay-for-a-good-bip39-seed-phrase-mnemonics-generator