Originally posted by Eightball:

There was a new terrain generator introduced with the content drop. If you play an old save it will most likely be the case your Mistlands will be small, sharp and broken islands.

A new start would provide you with the best Mistlands experience.

Only if you’ve ventured close to the mistlands prior to updating. Terrain is updated as well, so as long as it’s undiscovered, it will generate correctly. The issue is the discover range is larger than most people realize and thus they venture too close and ruin the mistlands