... this happened after I had leveled up Minsc for the first time. Before that, his protrait looked normal, but afterwards... well.. looks to me like part of his bow (as seen in his full-body rendition in the inventory) got superimposed over his face, somehow.
Hope this link works:
https://preview.redd.it/446jiktlh61...18ce18b905241bd304f28144af0028864a557d42Is there any way to make the game "reset" his portrait?
I tried dropping him from the party and re-recruting him, also tried to re-spec him. Once without and then with a change in class - also once stripped of all armor/gear, but the buggy pic kept rearing its ugly head.
Also tried to re-start and/or re-load the game multiple times, throwing him off the team before a long rest, etc.
None of which worked.
S.