Belly of the Beast Level 2 - Road blocked to boss

I've finished the Normal game with a higher level party but when I got back in the game after a few months I found the following bug/issue.

I went to the last waypoint, entered Belly of the Beast Level 1, killed all 3 bosses, then entered Belly of the Beast Level 2. But I couldn't pass by the roadblock to encounter boss Piety, the Abomination.

So a Level 70 friend saw the issue live and told me that I had to go back to Crystal Veins, then enter Belly of the Beast Level 1. I did this but the dungeon was regenerated. So I had to kill all 3 bosses again. I've activated the waypoint "The Harvest", killed all 3 bosses, then went to Belly of the Beast Level 2 and saw the same bug. The road to Piety, the Abomination was blocked.

So how can I pass by this issue? It's strange that I couldn't find a forum topic like this through Google search so I hope that mine will showup for others as well. Maybe this is a bug due to finishing the game's final Act with a higher level party? I was level 35 back then, Iam level 38 right now. Do I need to be level 40?

Please help with this.
Thanks.

There's some confusion here:

Killing Piety in Belly of the Beast 2 is required to access The Harvest.

Killing the 3 bosses in The Harvest allows you to access The Black Core near The Harvest's waypoint.

It sounds like you've already gained access to The Harvest. Is that correct?

If you come from the Harvest to the Belly of the Beast, the road to Piety will be blocked. Do not go to The Harvest.
You need to do exactly as your friend says and go back to Crystal Veins, then enter Belly of the Beast Level 1.

Anyway, I already entered Crystal Veins first, then Belly of the Beast Level 1, killed 3 bosses then went to Belly of the Beast Level 2 but the road was blocked. I did exactly what you say.

I only finished the game with a party of 4 people before the last expansion. It was last year. Can someone from the QA login with my account and see what is the issue?

Okay that's the progression:
You go to Crystal Veins and enter Belly of the Beast Level 1. There aren't any bosses you have to kill. Go forward to belly of the beast level 2. Kill Piety the Abomination. After that you can enter The Harvest and kill the 3 bosses that drop those organs. At the waypoint of The Harvest there is another Piety where you can turn in the organs so the entrance to The Black Core will open.

Since You have already The Harvest waypoint activated, you killed Piety the Abomination already back then. I think you are looking for the freindly Piety, who is standing near the Waypoint of The Harvest (slightly north of it).

Edit: Reading your first post again i have to mention: The Harvest != Belly of the Beast Level 1. "The Harvest" waypoint leads to The Harvest map, that is why it is called that. At the Crystal Veins there is a hole in the wall which leads to Belly of the Beast Level 1.

Here's how it looks if you do it right. Click on each photo for enlarged version:

First, go to Crystal Veins:


Then, go through Belly of the Beast 1 to Belly of the Beast 2. DO NOT GO TO THE HARVEST:


Go through Belly of the Beast 2 and you will find Piety


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Here's how it looks if you do it wrong:

Entering Belly of the Beast 2 from the Harvest. Wrong way, go back, don't do this:


Dead-end if you try to go backwards to fight Piety:

Look at your quest map and see if it has any outstanding quests needing to be completed in A4

This actually applies to most boss fights in the game. You can't go back to the boss from the next waypoint, but must go through the preceding areas. Boss farming would be too lucrative otherwise since there's usually a waypoint right after a boss.

Why do you want to kill Piety anyway? Is it for the reverberation rod upgrade prophecy?

If you are asking me why killing Piety, the Abomination...well can I finish the game without killing that thing? If there is any other way finishing the game I'm eager to hear it because this is way too confusing and I'm 90% that I did all this!

With the way dudiobugtron writes the story, it's like "You have to go straight to Belly of the Beast Level 2 WITHOUT killing ANY boss in Belly of the Beast Level 1". Or I misunderstood it and when you go to Belly of the Beast Level 1 there are no bosses in the first place?

The way developers made it is very confusing imho. They should should remove all roadblocks and let people finish the game with the way that they won't. There is no other place in the game that has roadblocks in bosses and I find no reason for them. I want to hear developers' opinion about this. I repeated the procedure 3 times.