I've also lost the scout role in my own party.
Before 1.4.2 I've assigned that role to some companion I had. Then at some point I think i've created a caravan and appointed him to it, without changing his role back to None.
1.4.2 came out and I haven't even noticed that role is gone. I've noticed it way later, when I've hired companion with decent scouting skill and wanted to give him that role. It was simply gone from the list, but only in my own party.
I've seen somewhere that it might help if you talk to the person you've previously assigned that role to, and then try appointing a new one through option in conversation, but I believe that in your case it would be difficult.