For words that only have three letters, there is absolutely no 4th letter. For instance with the word “increase”, there aren't any additional letters Later on and therefore should be the word "insert". The word “addict” is from the BIP39 wordlist but you would've applied “addi” for “addict”. By next https://getsocialpr.com/story20117439/invalid-bip39-phrase-things-to-know-before-you-buy