Sorry Alloc.. I'd not seen your reply, and gave up on it for that time (would rather play than mess about for the map).
I tried with the new server release to get it all working again, but same issue.
I am logging in with Steam, it then returns to the map screen, but shows "Not Logged In" down the botton, with the login button for steam credentials again.
Exact same scenario as described by Backbite.
I'm not exactly proficient with linux, but I've followed the guides to get stuff up and running lol.
All is working fine (game servers, accessibilty etc) and all is great, except this map won't load.
Session ID is provided, and valid. Not blocked. etc.