For words that only have 3 letters, there's no 4th letter. For example with the word “incorporate”, there isn't any a lot more letters Later on and thus should be the word "insert". The word “addict” is in the BIP39 wordlist however , you might have utilized “addi” for “addict”. https://socialbaskets.com/story4521245/fascination-about-invalid-bip39-phrase