Zabbix - Grafana Issue


I have an urgent issue, I have created multiple dashboards on Grafana with some singlestat panels for UP and DOWN of some Servers and URL Checks.
In the same dashboard, there is a zabbix problems panel, showing all issues from servers. Now, the problem is that the page almost never comes complete. There are different single stat panels with “No Data”, as can been seen in the image attached. When I refresh the page, some data come for some panels and some other panels are getting lost, some other times, everything works.

The problem it shows is “Query error: 502 Bad Gateway”, but as I said, sometimes it works, sometimes it doesn’t so I don’t think it represents the actual issue.
I am guessing it has something to do with the Query being done back to zabbix? Maybe some limitation at Zabbix configuration? I can’t pin-point what is wrong with it. It is not constant, everytime a different panel is getting lost.

Any help will be appreciated!!

Capture|690x288 !

Thank you!

Thought was fixed because there was no “Application” selected, issue seems to continue but not happening as much.