Blizzard have applied a hotfix improving the Nightfall scenario.
There were problems with starting the scenario and getting through it, as players could get stuck without any progress. This fix should address that, but may not be live on all realms just now.
Over the last hour, we’ve implemented performance improvements to the Nightfall scenario that are aimed at addressing issues with it starting and progressing.
These improvements may not take effect immediately on all realms, and we will continue to monitor this very closely.
