I recently downloaded and started using the Arctic adventure pack. It seems completely void of all villagers to include the one you first meet and explains his world. I've watched youtube videos and there are some villagers but I cannot see any. The bug is specific to invisibility because I can interact and trade with villagers if I can find them. 
The mobs for the scrolls and the scrolls themselves are invisible. I can interact with the mobs as well. Regular mobs are not affected as I can see them normally.

 The throne room chairs are also invisible but I can get in and out of them.

this does not affect other worlds that I have and I can play them normally.