Upgrading from 7.16.1 to 7.17.5 Broke Kibana Monitoring Tab

After you configured Metricbeat monitoring, did a new index show up on your monitoring cluster? it should be .monitoring-mb-es or something similar. if you have a metricbeat index it means that system monitoring is configured and you're just getting system monitoring data, not elastic stack monitoring data. You will need to go through all these steps: