Sometimes when I change party members, the new members have a black portrait. I mean the image in normal gameplay where you select party members or chain/unchain them.
When this happens, some other things are not displayed as well often, such as poison clouds.
Saving and loading the game solves the issue

Prof. Dr. Dr. Mad S. Tist

World leading expert of artificial stupidity.
Because there are too many people who work on artificial intelligence already