For words that only have 3 letters, there's no 4th letter. Such as with the word “increase”, there are no much more letters afterwards and so need to be the word "insert". The word “addict” is while in the BIP39 wordlist however , you might have employed “addi” for “addict”. https://advicebookmarks.com/story26625818/how-much-you-need-to-expect-you-ll-pay-for-a-good-valid-bip39-seed-phrase