Device is online but the color is showing yellow

I am trying to connect OpenPDC with my testbed setup where I am using RTDS for power simulation and RTAC as an substation gateway receiving data from RTDS and streaming it to OpenPDC.
Although I can see the data is being streamed fine. I checked with creating a fault in RTDS and seeing the impact on real time graph measurement fluctuation in OpenPDC. But my concern is the testpmu device is showing yellow in OpenPDC. Why is that? does it means it is not working properly. I have attached two images. First one is showing the device dasdboard and the second one is showing the testpmu configuration.

Best Regards,
Mustafa Hussain