For words that only have three letters, there isn't any 4th letter. Such as with the word “increase”, there aren't any extra letters Later on and thus need to be the word "include". The word “addict” is from the BIP39 wordlist however , you might have applied “addi” for “addict”. https://companyspage.com/story4446968/5-simple-techniques-for-bip39-seed-phrase