The game invariably crashes while trying to change a viper's eye colors if you have One Million Colors or any of its extensions.
The other extensions I'm using, for the sake of clarity:
OMC Plugin for WotC
One Million Spark Colors

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Very unfortunate that this incompatibility exists. I either have to have very limited color-picking for 90% my soldiers (which is completely asinine considering I very meticulously choose my soldiers' armor colors) or my sneks can't change their eye color.