The third time I've encountered this frustrating bug, and only seems to be happening in the Lone Story mode in Duviri. The group would progress like 3/6 or 5/6 when these missions come up and when someone completes it, it just stays locked and we can't access the rewards and move on with the mission. When I encounter the "Find the Hidden Chest" in the first 2 stages it's all fine but since I have a very small sample case of this bug happening around 3/6 or 5/6 I can't be for sure if it's happening more often in the later stages of the missions.