Hi Peter!
Since I don't know anything about your solution, have you tried to update the VCN to the latest firmware?
Are you using the admin account or another one to watch the cameras?
You can check if the user has rights to view the cameras in the group by going to Workspace and from the left panel chose Users under Users and Devices.
Once the Users page opens, check if the used user has the rights for the group to view the cameras as per below:
Please let us know if the issue is solved or if you need further help.
If you need further help provide more details:
1. How you create the groups.
2. How you add the cameras.
3. How you create and assign the user(s) to the groups.
Maybe there is something wrong in your process, maybe it's a problem with the configuration. We can't know unless you provide more details.
Cheers!
R