Cant complete Niko's Fuel

I rushed past niko in Act 4 and now I get a talk to Niko prompt almost every time I go to my hideout. When I go to Act 4 to do the quest I see the "Collect Voltaxic Sulphite 0/5" but no sulphite nodes spawn anywhere in the Act.

Any advice to fix this?

Had the same problem.
I actually had to go down to the Mine Encampment, and talk to Niko THERE.
Maybe that´ll work for you as well.

regards,
Rick

Yeah, I've talked to him at mine outpost, in hideout, in Act 4 nothing works.

Yes, talking with him there didn't work for me either, and doing highlighted delve also didn't work. What did work for me was completing his daily mission in a map.