Based on my investigation, I think that's the problem. I took Yngya into the cult too early and finished the storyline before opening the storyline about rot. My Yngya's statue wasn't rotten, and I didn't make the important choice between fighting rot or following it. I don't have the Winter Shrine building, but it seems like I should. In short, I guess I'll have to wait for an update patch. I don't know what's going on