Huh, looks like the game is trying to load up a battle using an empty fighter with no race or gender. I've updated all the fight scenes in the last update, so I probably left one of the template fields empty somewhere.
Either that or your player character isn't loading into the fight scene properly for some reason.
*EDIT*
Looks like it's the player character causing the issue. The problem seems limited to male characters (at least in the tests I've run), so it's probably something up with the entity for player human males rather than the save data not loading correctly.