I have what I would consider a default installation of the latest version of MongoDB Ops Manager and MongoDB.
Everything is working except the Hardware > CPU monitor for my server.
Attached screenshots of the configuration and the screen showing no data.
Ops Manager Version - 3.4.6
Auth Schema - 5
Feature Compatability - 3.4
Advanced startup options (default) -
nojournal - false
logappend - true
syslog - false
slowms - 100
profile - 1
Log Path - /var/log/mongodb/mongod.log