For words that have only 3 letters, there is no 4th letter. Such as with the word “increase”, there won't be any additional letters Later on and thus need to be the word "insert". The word “addict” is from the BIP39 wordlist however , you might have utilised “addi” for https://bookmarkstime.com/story19208553/invalid-bip39-phrase-things-to-know-before-you-buy