Alerting email graphs : Graphics are not always shown

Hi there

When I get email alerts from the system, the graph is not always shown...

I just had some issues with some fans ramping up, so I got 4 alerts (one for each fan), and three of them had no graph but just the little "?" signifying that the graphics is gone or broken...

I use an MS Outlook client on MacOS, but is it also apparent if I use the Office365 web version...

I have attached two examples that shows one of each...

I have not tried to alter the alerting in anyway... pretty default setup that has been running for just about a year...

/Beardmann