I have been flying around 5 worlds and found three igloos that are generating normally, im not sure if this was just a freak structure placement or a bug. One possibility is maybe that the structures bounding box is colliding with the snow layers thinking that it is blocks it needs to place on top of. but i cant confirm that possibility yet.
-Signed off by EmberFlash [email protected]

Every igloo I've seen in testing (a grand total of 3) has looked ok to me. Closing this for now and hoping for the best!!!