Zabbix's Dashboard isn't loading any information

[wpagane]

Hello all,

My Zabbix (5.2 version) environment has around 60 hosts.
All triggers were added as my needs, such as ACTIONS (to start Windows Services automatically, in case of DOWN), Send emails for Critical alerts etc.... It was everything working fine for 2 months...

Today, suddenly, when I acessed the Zabbix Front End > DashBoard, I noticed nothing is loading in the main screen. No alert information is being displayed and there is an icon of "loading" forever (please check attached screenshot).

I have already rebooted the Server, rebooted MYSQL, rebooted Zabbix Server, CasheSize i have changed it to 1G, ValueCasheSize = 512M, StartPingers=100, StartDiscoverers=20.... nothing happens.

I know Zabbix is working because when I click in "Hosts", I can see everything, including the "Problems" through there. Also, I can see all information from Zabbix into Grafana as well - That means Zabbix keeps sending the information to Grafana and I can monitor through Grafana normally. BUT, Zabbix's Dashboard isn't loading anymore.

Have you ever faced this issue?

Thanks a lot!

[wpagane]

To be more specific, only the "Problems by severity" and "Problems" dashboards are NOT loading data anymore. Other Dashboards are working fine (please check attached file).

I'm starting guessing this is something related to the DataBase? Is there any procedure in order to verify mysql (in my case) DB? Rebuild Index... etc.... I don't know..

[wpagane]

Through Debug mode, apparently the queries are running well. Attached file.

[wpagane]

RESOLVED!
I enabled Housekeeping for "History" and changed the Data storage period FROM 15 days TO 3 days.
Not sure if this was the resolution item, but after ~12 hours of replication Zabbix's Dashboard started responding again slowly, and after ~18 hours it was working perfectly again.