Worked great for years, the current version is broken on Firefox and Chrome. As many others have reported, it does not find any matching sites in the vault. You have to manually open the vault (which is also slower now) and find your site.

Update: To fix this disable the "improved save and fill" feature. It eventually worked for me, not sure if it was a restart that did it.
https://support.lastpass.com/help/how-do-i-enable-the-improved-save-and-fill