This just happened to me. I wondered why things had suddenly gotten so hard - then i realised back in skyhold my armor/helmet was missing. What made it so galling was it was rare crafted armor and i don't have the materials to craft it again. The last save point i had with the materials was three hours prior so i really don't want to have replay it all again just to get it back.
I hope this is a one off. I love this game, but i really don't want to have to be checking my entire teams inventory everytime i start it up.
