Is this only happening on one machine, and have you already tried uninstalling the LastPass extension then clearing your browser's cache, restarting your browser and reinstalling the LastPass extension from here to see if it fixes this issue? https://lastpass.com/download/
I fixed it shortly after posting by removing all extensions, including LP. Then put back LP by itself and it worked. Slowly added other extensions until I found the one that was interfering with the loading of LP. I was able to put back all except the one culprit and everything is working fine,
In testing I removed all extensions and rebooted before adding in LP.
Hope this helps.
Different people are experiencing slightly different symptoms. In my case, I disabled all extensions except LastPass, and still had the blank window. Removing LastPass cookies and clearing cache did not solve the problem.
Since uninstalling/reinstalling LastPass is has worked as expected, without conflicts with other extensions.
I wanted to let you know that we identified the cause of this issue and it is the result of an update process in the browser. We are releasing a fix in our next extension update, but my understanding is we will not know for sure if it corrects the issue until it is live on customers computers and the browser updates again. Uninstalling and reinstalling the extension removes the issue created by the update which is why the issue goes away, however it would most likely return after the next browser update without the fix that is being deployed.
OK, it worked for me to do what you say, following the steps of uninstalling the extension, delete cookies, etc..
I had to uninstall it for the second time, because the first time, the icon space was blank, but nothing would appear when I clicked on it.
In the second installation of the extension in Firefox, it worked correctly.