A Thorne-y Relationship map and chest gone?

I started the quest and uncovered the chest then fought off the enemies but found a duty so I did not open the chest and instead went into a duty. When I finished the duty the chest was gone and so was the map so I am unable to continue the event. Is there some way to reacquire the map or chest or am I unable to do the event now?

(I'm not too sure if I should post this in the Bug section or quest section)

You can purchase the map for 200 gil from the same NPC that sells the event items.

She's right to the left of the quest NPC.

Thank you!!!