Repro
Have an account that hasn’t completed Vessel of Hatred yet.
Complete VOH campaign with a seasonal character and skip priority quests (or maybe not even get them)
It becomes impossible to unlock Kurast Undercity as the quest to unlock it is no longer there.
This means it becomes impossible to complete the season ranks to unlock torment difficulty.
Additionally - This makes the quest Deeds of a Champion impossible to complete as the NPC required is not there.
does your undercity icon on map say “requires VOH”?
this is related to this same bug: https://us.forums.blizzard.com/en/d4/t/the-priority-quest-for-unlocking-the-undercity-in-kurast-has-vanished-so-now-we-cant-carry-on-as-npc-is-missing/236466
Turns out I was unable to unlock by doing the 2nd Capstone dungeon.
However, I’m still locked out of accessing the Kurast Under city.
does your undercity icon on map say “requires VOH”?
Yes it does, at least where I think the undercity is.