Had the same issue as the people in this thread about an issue with the NPC character sheets and I found a fix. If you toggle the switch on the NPC's sheet back to PC you can set the current HP to the max value and once you switch back the wounded state is fixed, if that doesn't work manually changing the "hitpoints" value in the Attributes & Abilities tab on their sheet should fix it, hope this helps anyone with the same problem as me, I know the previous post had a fix for this but this fix stays persistent after you close the character sheet. I've found the best way to track their health is to set one of the bars on a token that represents their sheet to the "hitpoints" attribute and use that bar to track their health, it will even update their rolls appropriately when they get to a wounded threshold.