I was running the new story with my Girlfriend and we got to Snapping Steel, we went through the whole instance but she was unable to receive credit. Now she sees the step to go into the hidden base, but has no instance start Star or ability. We tried to piggy back off a nice passer-by to see if we could get progress to count with them but that also did not work. She says she does not see the normal "claim credit" screen you normally get when you complete these as a group.
Others in Map chat were talking about this being an issue that was preventing progress with them too.
This is preventing story progression as you cannot reset the story for yourself until you have completed it, but cannot complete it because of the bug.
I do not know if there is a way to replicate, i would try to have someone complete it in a party and see if the non-Host gets credit.