For words that only have three letters, there is no 4th letter. Such as with the word “increase”, there won't be any much more letters afterwards and so has to be the word "insert". The word “addict” is while in the BIP39 wordlist but you might have utilized “addi” for https://kingbookmark.com/story18933843/the-fact-about-bip39-seed-phrase-word-list-that-no-one-is-suggesting