If you view one of the listed servers performance, can you see these metrics being populated?
To find out search for one of the servers you’ve specified and when on the server page, click View Performance in the top right. From here you may need to click “Show all” next to Favorite metrics under the server name in order to see the memory and CPU metrics.
Be sure to test if you can see data from both the time frame you are after, and a slightly extended time frame. i.e. 24 hours and 30 days. This will show if there’s an underlying issue with SCOM that needs to be addressed.
Just so you are aware, when we’re replying to a question we post in the comments until an answer is found. This means we get straight to the information that’s key when reviewing a question we need the answer for. One of the admins will move this answer into the comments at some point 
A full “How to” of how to use community can be found here:
https://community.squaredup.com/community-answers-guide/