Add new policy not working after migrating from v8.2.1 to v9.0.3

I have around 7k alerts in grafana v8.2.1. I wanted to migrate to v9.0.3. So i installed v9.0.3 in new ubuntu VM and copied database file from v8 to v9 and I started the grafana server. When i go to notification policies i see 7K policies created and each linked with alert rules. But when i try adding new policy, the button just disappear and no form show up.

After i click “+New Policy” button.

I also tried roll back to legacy alerting by following below link, but it also did not help: