Board Thread:Questions and Answers/@comment-26112340-20160205010136/@comment-3263817-20160222204922

They weren't even in Mixtopia/Mixelland anymore. The keyhole portal sent them to what could have either been simply another planet, or another dimension, and then they were left in a white void that the Weldos appeared to have access to.

The white void appeared to have been the Weldos' sandbox or construction site, as they are a "hidden workforce", and they appeared to have had some strange portal of their own like the keyhole portal, but in a pothole form. The Weldos likely still have their portal access to Weldo Land in Mixtopia, but have left the land to live in Mixopolis with all of their Mixel friends.