Hi, there is work going on at the moment to support Sierra.

Some of that is already fixed and will filter out through the next few versions.

I can't advise on items like LastPass as it is a third-party add-on and I don't know how it works - it may need fixes within Firefox, or it may need changes in the add-on itself. I'd suggest reporting it to the add-on author in the first instance, and they can always refer it to Firefox developers if it needs a Firefox fix.

Thanks for the reply. Hopefully something will come soon. Already waiting for a reply from LastPass.