Quick update as promised. It's now been 5 days since Firefox itself was reinstalled and so far the extension has worked normally. I am under pressure from the support team to close the ticket but have asked for it to be left open until at least Friday so will provide a further update then.
Why would they want to close it, when no solution has been reached? This is why problems like this never get solved. Makes it easy for Firefox to ignore.
Like here in the community where we ask you to mark something as a solution if it resolved your issue, we ask if a ticket can be closed because otherwise they can be forgotten and just sit there.
If you're not ready to close a ticket you can reply to it and say so.
I'm pleased to say that the extension has remained stable for over a week now so I've confirmed to LastPass that I'm happy for them to close my support ticket on the basis that the problem I reported is no longer occurring. If it does show itself again I will update this post but hopefully reinstalling Firefox followed by a fresh install of the extension will work for everyone else too.
I have done a reinstall of Firefox followed by a fresh install of the extension before, it didn't help in my case.
Wouldn't you know it, by coincidence, it happened again. I was hoping from that last post by jamiesop1 that perhaps Firefox of LastPass had addressed the problem in recent updates, but no.
STILL happening. Hey, LastPass, how can you expect people to upgrade to the pro version when this keeps happening and you don't do anything about it???