If you in single player when wyvern nest not spawn just uncheck use single player box after get wyvern egg make sure you check this box because it will affect your game. You can get imprint 100% with your old setting if this box uncheck. I do this and I get a lot of wyvern eggs in Ragnarok map. But for Ice wyvern nest It still not spawn. If you know how to make Ice wyvern nest spawn please tell me.