when I try to edit/delete shared group data from game manager, it throws an error "This group data must have at least one member.".
The group was created by cloud script and has no members.
Attachments: Up to 2 attachments (including images) can be used with a maximum of 512.0 KiB each and 1.0 MiB total.
We can reproduce the issue that you encountered and will report this to the related team to investigate. As for now, you may use APIs to delete/edit groups with no members in it:
5 People are following this question.
InvalidSharedGroupId in Server API
GameManager fails to display shared group data
Groups not showing in Groups, but are listed under player
Items with a consumable time < 1 day are being displayed in game manager as "expired"
Why can I not see Catalog Bundles, Containers, or DropTables In Game Manager?