@garbo1984
I have the same issue AND i also opened the chest first after the cutscene rather than following him so that actually might be the issue.
Also i cannot interact with any merchants etc, but like you i killed/looted everything else on the map i could (including killing the legendary animal with bare fists :P).

Also i have bug for the "Saint Faith" - world event

at the first encounter i was able to interact with the priest (but he were near the tree and not where he should).
After the talking i went to the nun but nothing happened so i restarted the game, now they are in the correct positions but i cannot do anything, there's no interaction with the priest anymore so i cannot finish the world event. The priest just keeps yelling no matter how many times i restarted.

I tried to verify the game files for both bugs, but they are still there

I'm playing on PC with Xbox controller.