For words that only have three letters, there isn't a 4th letter. For example with the word “insert”, there aren't any extra letters Later on and thus must be the word "include". The word “addict” is in the BIP39 wordlist however, you would've utilized “addi” for “addict”. A straightforward backup https://bookmarkingbay.com/story18942546/invalid-bip39-phrase-things-to-know-before-you-buy