Wowza Community

Is there any reason for 2 of my 8 Wowza Media Servers don't show the CPU graph usage?

All the usage (memory, connections, disk, network) graphs are showing but not the CPU graph and usage - “Home” and “Server Monitoring” options. Those 2 systems have equal configuration to the other 6 and the systems (hardware and software) himself are all equal. I’m using Wowza Media Server (Windows)

Correction: I mean Wowza Streaming Engine, not Media Server, of course