You will have to use apex sharing for this. To show it on self service under others.
Simple test - add "Incidents tab" standard salesforce tab and see if you can see those, if yes your group sharing rules are working hoever to get it working for others on Self service you will need apex sharing.
Can you please give some more info on this.
You cant share records on SS with sharing rules. It will not show up in GUI. You need to use apex sharing using code or flows.