For words that have only three letters, there isn't a 4th letter. Such as with the word “insert”, there won't be any far more letters Later on and thus should be the word "include". The word “addict” is during the BIP39 wordlist however, you might have utilized “addi” for “addict”. https://ok-social.com/story4298695/5-essential-elements-for-bip39-explained