I am seeing the same problem across multiple iOS devices in our family.Whenever someone tries to add a new password for a website to Lastpass, the same error occurs saying "LastPass couldn't save your password". Link is available to "Try Again", but it always fails. We can load the LastPass app and add the site and password there, but not directly in Safari via the popup.
The lastpass extension is installed and it does work properly in auto-filling passwords as needed. The only problem is as described above when adding a new password. The popup appears asking if we want to add a new password. When we click yes, it thinks for a second, then pops up the error above. No matter how many times we click "Try Again", it continues to fail and bring up the same error message again and again. I'm seeing this issue for our family account across multiple people's iPhones and iPads. All devices are up-to-date (Lastpass and iOS).
Can anyone help? It's a big hassle for this not to work! I'll note that we don't see this error on our Mac computers, only in iOS.