Graphs lagging behind

Hi
I was wondering if anyone else has a similar issue to us:
We’re running Dude on a CCR1036-8G-2S+(6.48.3), with the database on a SD card.
The interface graphs that monitor throughput seem to start lagging behind, and get further and further behind real-time until I reboot the router. After a reboot all the data between the lagging time and present time is lost, and the chart stays up to date for a little while before starting to lag again.
Here are some screenshots:
Screenshot 2021-05-27 122920.png
The straight line at the end to present time is the distance of the lag.
Screenshot 2021-05-27 123049.png
The blank space is where it was lagging before, and I rebooted.

Any ideas on how to troubleshoot an issue like this?