Can't Finish Daily Because of Group

Almakor

When I did the Feasting in the Dark Western Skyrim Quest with a group, when my group members cleaned the souls they weren't counted for me and I became unable to complete quest.

SilverBride

I've run into this before. If any member of the group picks up the side objectives before the group is full then the new members aren't able to complete these. I never pick these up until the whole group is there and ready, but getting others to do the same isn't an easy task.

Mithgil

When this happens all you can do is drop the quest and pick it up again. You can always get any current group member to re-share the quest with you.

Bat

I've seen this happen when members of the group haven't been in close proximity to the additional objectives. So if they arrive late to the general location of the quest objectives, anything that's been picked up/cleansed/et c. by other group members will become unavailable for the late arrival.

ZOS_Bill

As mentioned above, you'll need to drop and restart the quest in order to proceed further.