widget 'real time graphs for CPU' stops drawing somewhy

Hi guys,
in my opinion OPManager is a great product, congratulations!
I installed OPManager10 to monitor several Windows 2008R2 servers with SQL Servers,
registered windows servers in OPManager, defined performance counters to monitor with WMI, created several dashboards and CCTV view.

It worked fine for a while, but in time widget 'real time graphs for CPU' began to stop refreshing for 3 servers only somewhy,
I mean after OPManager service is restarted 'real time graphs for CPU' draws CPU Usage on these dashboards for few minutes and then stops drawing and widget stops in time.
I checked CPU performance monitors for these servers - these monitors read their values and write history, but on the dashboard widget 'real time graphs for CPU' doesn't show it any more.

My question is - what should I do for widget 'real time graphs for CPU' to keep drawing current values?(refresh doesn't help)

I noticed that these 3 servers return CPU Usage monitor values(test monitor) with 3-10 seconds delay some why, how to correct this?