I've been having this problem for quite sometime now (since custom factions were enabled for MP). I create a custom faction for multiplayer, along with custom picture and logo. Start a fresh multiplayer game, and then I get stuck on the first screen as it won't progress past Loading Custom Faction Data...

This has also been the case for another friend of mine doing the same thing.

If I load a MP game on my own, with just my own faction and AI, I still get the same issue.

However - If I load a custom faction WITHOUT the pictures, I can get in fine.

Considering that others I've spoken to are experiencing the same, surely this is known?

Edit* Seems that doesn't matter if using custom pictures or not, stock pictures with custom factions simply doesn't seem to work in multiplayer with 2 players.