I am having a similar issue. Since I’ve caught Enamorus, it seems all of the time rifts have stopped. I’ve ran around the map collecting every resource I’ve come across and battled every alpha I could find. When I got bored with this, I remained in one location and waited. All of this took about an hour and still no time rift. I’ve read that after 40 minutes, a rift is guaranteed, however, this has not been the case. I’m unsure if my game became bugged or not, but I’m 3 Pokemon away from being able to meet Arceus for the first time and I’m sincerely hoping everything sort of works itself out.