Total Performance -> Disk Latency is empty

Hello, guys!
Some of my PMM2 graphs show nothing.
This is what my Disk Dashboard (Total Performance) looks like right now:
Disk Latency, Avg Disks Operations Merge Ratio and Disk IO Size are empty.
BUT… if it’s a specific device (sda, as the following screenshot shows) everything is OK:
How do I fix those empty Total Performance disk graphs?

Hi Ruslan,
I have reproduced the issue. I will get back to you after an investigation.

The issue is related to NaN values provided by formulas for an idle disk.
Here is dashboard version with fixed formulas

Thank you, adivinho!