After a recent Firefox update, there was no "restore" option. When I take the steps to restore the last session, the option is greyed-out. Luckily there is a decent-sized file named sessionstore.jsnlz4 in the folder from a few weeks ago, so I followed the instructions here to restore that file. BUT, even with that file placed back inito the appropriate folder, I still never get the option to "restore". I feel pretty sure that the file (1.18 MB) has inside what I need/want, but how can I get Firefox to "restore" using that file?