Hi Arjit,

I see that you created trigger rule for the group 'Demo Branch Application'. When you create incident are you populating assignment group as 'Demo Branch Application' manually or is it populating through trigger rule.

If assignment group is already populated then On-Call scheduling trigger rule will not work, there is known error about it.

PFB link for workaround.

https://hi.service-now.com/kb_view.do?sysparm_article=KB0547296

If my answer has helped in any way, kindly mark it as helpful/correct as applicable. Thanks!