For words that only have three letters, there isn't any 4th letter. Such as with the word “insert”, there aren't any extra letters afterwards and so need to be the word "add". The word “addict” is from the BIP39 wordlist but you might have used “addi” for “addict”. This additional https://socialexpresions.com/story4369462/invalid-bip39-phrase-things-to-know-before-you-buy