I have a little bug with preview image

Hello dear developers.
First, please excuse me for my bad English.
Second: I wanted to write a little bug that occurred after an automatic update to version 2.1.0
As you can see in the screenshot that yavam sent on the statistics page does not display the preview image.
I have updated to the latest version 2.3.0, but the problem persists! Help me!

When you click “right click > View image” do you see an error?

in Settings > System check, do you see only OK checks?

With the system all ok. When I click on the picture throws me on the same page. That is, the page just refreshes and all.

Do this: “right click” on a Sparkline image, then click “View image”, then what do you see on screen?

If no error, maybe you see an error in your server error log file?