Hello @aromadelexito,
Welcome to the LastPass community!
I understand this is happening when using the LastPass app. Are you using iOs or Android device? Also, have you try from a computer to reproduce the issue using the browser? I try right now to reproduce the error using an Android device but I was not able to reproduce it. I will also recommend trying to remove the item and add it again it's possible that the URL change or is not directing you to the right place. The 400 error is related to URL issues.
Kind Regards,
Alejandra
LastPass Tech Support