Hello Kevin,
we also had this problem after updating our Server to 2.3.0p11. This only occurred for Excahnge Services.
I solved this by increasing the wmi timeout on the Exchange Server (not cmk Server):
In C:\Program Files (x86)\checkmk\service
edit the File “check_mk.yml”
increase the line wmi_timeout: 5
from 5 to 8 (seconds)
Maybe you have to increase it more on your systems.
You can also set the timeout by rule and roll out the agent again:
Setup > Agents > Windows, Linux, Solaris, AIX > Agent rules > Windows WMI Timeout
Kind regards, Marc