Niko quest bugged, Locked out of Delve

I got a lake of kalandra tile with Sulphur veins, before reaching act 4, and now when I talk to Niko , it says you dont have the required quest state

in the log window, it says visit niko's mine encampment, but the icon to teleport to that location is missing , asi never actually finished the quest in the mines. He never spawned inside, where he usually gives your first Sulphur

completely locked out of the content for now.

I also have this bug, I ran a sulphite spot in the lake, in the dried lake bed, and as a result the quest bugged out. When I try to talk to Niko in town and teleport to the mine it says I do not have the "required quest state".

Update: Literally half an hour after I posted last, I got to act 6 and found sulphite/Niko in normal zones and was able to progress the quest, so it's definitely a bug, but not as delve-ending as initially appears.