So I have encountered a bug when trying to knock out The Mask of Vengeance, as soon as I down her one of the characters around her freezes all together, they can not complete any actions, move or interact with the world at all, whilst the other party members can move freely.
(It also apears to be random who this effects, on one ocation it was my player char, then it was Gale followed by Wyll).

It apears to only be the mask of Vengeance as I have had no bother with the other masks.
I repeted this a good few times, I even atempted to knock her out after I had defeted the Hag which still led to the same effect.
I also tried going to camp and end the day to see if that would 're-activate' my frozen char, but she was still unplayable.

Hope this helps. smile Thanks.