Blizzard has announced that the Twist format will be disabled for the upcoming December and January seasons. Don't worry though, it will be making a return in February with "a fun new season". We're not sure what is preventing a season from taking place, but it is certainly disappointing to see support waning for the newest format to join Hearthstone.

Quote From Blizzard

Journey to Un’Goro has come to Twist for the November season, now live! Head to Twist now to dino-size your climb. After the November season, Twist will be temporarily disabled for the December and January seasons. We look forward bringing Twist back in February with a fun new season!