I dunno. Here's what I experienced:
Prior to going Offline: clear cache, download missions, close browser
I can either pull the ethernet plug OR put FF into Work Offline mode, and the following is the same:
Open browser (either plug is pulled, or, put brower into work offline mode at this point)
Open MM Login page, goes to offline "Logged In" page... however, no links available on this page to go to a mission... aside from mission tabs at the top, the buttons are for Logout or Change Password.
Randomly select one of the mission tabs above (eg, Checkin-Offline.php)
Go to that page
Click Leave Mission at bottom of page
Takes you to Mission Manager page, click Offline Missions... No missions available in "Offline Missions"- the downloaded missions are not showing.
...So to sum up, the initial offline login page doesn't take you anywhere, and when you finally do get to the Missions-Offline page, there are no downloaded missions.
I am appreciating your patience in this, since it is enough to drive me to several adult beverages.
Matt