Ledge Progress Blocked by Side Quest Portal

I was running through the Ledge in Act 1 Merciless this morning and encountered a side quest portal that completely blocked progress through the level.

You could not get around the portal.
You could not flame dash around the portal.
Completing the side quest and exiting the dungeon put you back on the same side of the ledge map with progress still blocked.

The only solution was to reset the level.

You are inside the vaal side area in that picture... You need to click the doorway to go back to the ledge. Its a separate zone. You are not in the Ledge in that picture xD. Once back in the Ledge, you make it sound like the side zone portal has spawned like this:


Normally when a Vaal side area spawns in ledge it does so like:


TBH it sounds like you just got lost in the tileset.

That side area entrance is on a side branch of the ledge; you can see that it has water on both sides, while the main path of the ledge always has water on one side and rock on the other. You just need to backtrack to where the side branch branches off from the main path.