MSSQL Some Graph Panel are not updating renamed Datasource

In my team, we had to add more datasources to the grafana instance and did need to change a datasource name.
The problem is that although tables and Gauge panels updated perfectly, but Graph Panels with time series did not get updated and keep alerting DataSource does not exist when loading the dashboard. Even after manually changing the data source in the Panel query, the current datasource name does not appear in the datasource drop down.
Any ideas to trouble shoot this?
I already checked the JSON for the dashboard datasource name and it did update correctly.