Ffa, arena and slayer - i was in an ffa - finished game and they were gone.
Hey OP, 343 are tracking the issue in this thread 
https://www.halowaypoint.com/en-us/forums/6e35355aecdf4fd0acdaee3cc4156fd4/topics/playlists-gone—just-happened/943a8570-031c-4b25-82df-c08ead9fbb50/posts