Basically I had happened to find the Barrow Dyad puzzle at the same time I was running the RoD step 2 in the nether and I completed the run without the rifts. When I attempted to go back into either exploration or arena they don't seem to respawn anywhere in the nether areas. I googled to make sure that I was checking the right places; unfortunately I have also come across a minority of other players on forums across social media who have run into the same problem of finishing out without heeding the prompt and not being able to get the rifts to respawn either. Really frustrating to be hardlocked out of the narrative seasonal content; really hope it gets fixed soon because aside from a few bugs the contents been pretty solid! Just uh wish I could actually experience it a but more past the second step of this second act guys :'(