Yeah, it's only happening in the Ancient Era ... so far. I just fired up a quick test game and ran a couple of turns to see how things looked. As I said, all is cool until I check the Foreign Advisor's screen. It then shows me a blank leaderhead with a big question mark instead of the guy. Doesn't happen on any of the other leaderheads I've installed tonight.
You're right about the backgrounds - Conquests does, indeed, use the same magenta background. That can't be the problem.
I've checked & double-checked my pediaicons file, but I can't see any mistake. I'll keep playing with it, though.
Anyone else seen this guy show up in-game on the Foreign Advisor's screen?