This is just my guess but I think with the new smoking changes in 3.63 you need some time to heat up the room like sauna. Did you try to smoke food immediately after you made the fire? Maybe the room was not heated enough.
Edit: I just tested with some bear meat and it looks like you don't need to wait for the room to heat up so I really don't know what is causing your problem. I've never smoked meat in caves.