My characters caught some sort of eye disease?

DDCreate

I've been working with these characters for the past few days, in different environments. Yesterday when they were at the pool, the whites of the girls eyes suddenly turned black. I thought I fixed it but then she and her husband both went shopping and now it's happening to him too (see attached). This has happened a time or two before but I wasn't really invested in what I was making so I blew it off. But I need them for this series and I need them to have normal eyes. The lighting source in the attached pictures are just a couple of point lights set at 20k. I often use that sort of lighting at the right distance to just brighten up their faces a little. Does anyone know what causes this and more importantly how to fix it? I've tried changing their eye materials, reloading them from their saved state and also remaking them from scratch. Loading them into a blank scene seems to work, their eyes are fine. But putting them in a scene, they look wonky. If anyone can help I'd appreciate it because I'm stumped and also can't move forward.

Thanks for any pointers.

FenixPhoenix

This tends to happen when the character is far from the world origin (where it loads). The solution is to put the character inside a group and move the group instead.

Paintbox

Short version : in render settings, change optimization from speed to memory (or viceversa)

Long version : There is a floating point precision problem when you move away from the origin (x,y = 0,0) and surfaces that fit snug together (like eye surfaces) can make it seem black. So another option is to move your characters to 0,0.