For IKON reservations, I had to delete cookies, browsing history, then log out, then log in. At that point everything started working, at least for Jackson Hole. As mentioned, can only reserve one day at a time. Not great, but you can work through it fairly painlessly. And I did everything on a PC. My phone's IKON app wouldn't get me very far. That's mainly why I called IKON - I figured they had me down for a plain IKON Base Pass, which doesn't include JH and Aspen.
As I recall, there was something price-wise that fouled up my original IKON signup back in April. Some coupon or SkiTalk benny??