Why Don't Some of My Groups Show when Creating a Snapshot?

Snapshots can only be assigned to Groups that have students in them, so if you have a Group without any students in it, you will not be able to assign a Snapshot to that Group until students join. In the meantime, you can assign a Snapshot to any Group, select "Plan for Later," then once your Group has students in it, you can edit the Snapshot from the Schedule, and select the appropriate Group.