I have noticed my character portrait going blank now and then - a save and reload fixes it. I have now pinpointed a cause, which is using the message log [v], then scrolling. Just opening the message log does not cause the portrait to disappear, but scroll before returning to game and it's gone.
I suspect this has something to do with Sami's recent fix for the portrait showing in the message log screen.
I am using the BAC mod, and ModernNorseman's Portrait Mod - the latter may be causing the issue but I don't think so as it seems to be just a load of .png files as replacers.
Anyone else getting the same problem?