Sorry about that, I was trying to troubleshoot without installing Firefox. This time, click the add-on icon in the toolbar that looks like a puzzle piece, and make sure LastPass is pinned.
Go into your toolbar customization settings, and add the icon back.
https://support.mozilla.org/en-US/kb/customize-firefox-controls-buttons-and-toolbars
I went there but found no LastPass icon to put back. I verified LastPass in listed under extensions and is enabled. Yet I don't seem to be able to activate its icon.
Thanks. That worked.