That issue can happen when a map has certain improper code associated with it. So, you could try testing on a different map that definitely works (such as the regular version of Seton's Clutch (scmp_009)).
If that doesn't work, you could also try reinstalling the game.
If that doesn't work either, you could share a log file from your game session so that we can evaluate that (the upper left corner of the FAF client has a button that you can click that opens a drop-down menu in which there is a 'show log folder' option).
Also, are you able to join/play in other people's team game lobbies on FAF without issue?