Claudio,
Please check if the the batch risk analysis jobs are running OK. With Dashboard that might be a good point to start investigating.
Also, if you have not already, please look at following notes.
1675760- Creating launchpad links for Realtime Risk Violation
1675758- User Risk Violation report always show real-time violations
1686073- Complete data is not visible in Dashboard Pie chart
1622950- Drill down issue in dashboards
1616435- AC10.0 - User / Role Analysis Dashboard drilldown
2150961- Consolidated Note for Access Control - Dashboard 10.1 & 10.0 Issues
Another thing you can do is
SPRO>Governance Risk and Compliance>Reporting check the entries under dashboard file path.
Regards,
Shivraj Singh