The plausible reason why you do not see any metric for CPU Utilization is because there are no triggered rules for the timeframe chosen. The rule id.303000 does not exist under the wazuh-alert for the chosen time frame.
You can confirm this from the Discover page by performing a filter for the rule.ID 303000 within the same timeframe you picked for your visualizations.
Also, to get a quick value shown on each of the graphs.
Kindly click on the Options button next to Data and then select "Show Values". This will at a quick glance provide you with the % score of each metric by their PIE chart.
I hope this helps resolve the issue. Do let me know if you require further assistance.
Regards,
Chuks OKonkwo