I’ve checked everything I can check, and I have no idea.
There is this article, but not completing the quest line should only lock you out of Level 1. If you completed that, I can’t think you should be locked out of Level 2. But since I can’t see your Retail character, I can’t check anything about it. https://us.battle.net/support/en/article/281593
At this stage, I think you should make a supprt ticket.
you haven’t completed the quest chain to enter Torghast.
According to Wowhead, it is
and if you look on the right, you will see the whole questline.
I DO NOT KNOW if this is the problem. I remember Blizzard mucked about with it during 9.1.5-9.2.
And as tfar as I can figure, not completing it should block you from Twisting Corridors at all. But here we are, so it can’t hurt for you to do the chain