There have been a couple of workflow improvements to the Groupshot process to enhance your experience and to improve housekeeping!
When you 'Create a Groupshot,' Motional will now let you know if there are any incomplete Groupshots for that Group. (This will stop you from creating unwanted duplicates!)
If you are a Team Admin or the User that began the Groupshot, it will let you pick up where you left off, delete, or continue as appropriate:

Furthermore:
Motional will now prompt you to confirm the members of the Group and give you the option to Edit the Group (see the Making Changes to Groups Support Article here for advice on Editing a Group):

This supports your Groupshot data-quality by ensuring blank data isn't recorded where Participants may have left the group.