PirateAnt3000

I know where the egg nests and ice wyverns are but literally none have spawned. Not even a single ice wyvern. Now, the other types of wyvern seem to be doing ok but it’s the ice wyverns that appear to not spawn because I have seen zero since I first started. I’m in single player so I should have no problem because I’m the only one on but again they don’t appear to spawn. Not even once. Help. I’m am also on Xbox.