Created attachment 1757981 [details]
Overview of the Plasma System Monitor - without data
Description of problem:
Testing the Fedora-KDE-Live-x86_64-34-20210217.n.0.iso I found that when opening the new Plasma System Monitor its doesn't show History (CPU, Memory or Network) information and it doesn't show System Stats (on the overview tab)(prints of the screens attached). I tried on wayland and x11 session too.
Version-Release number of selected component (if applicable):
Fedora 34 build => Fedora-KDE-Live-x86_64-34-20210217.n.0.iso
KDE frameworks => 5.79.0
Qt => 5.15.2
Kernel => 5.11.0-0.rc7 (150)
Steps to Reproduce:
1.Login to a session (wayland or x11)
2.Open Plasma System Monitor from the menu
3.Browse through the tabs overview and history
Blank data on both screens
Actual data on memory, disks, CPU and Network usage.
I found that the old KSYSGUARD DEMON still running (as see on the image attached), but no KSystemStats (print attached).
Seems that the service KSystemStats its not on this build.
I tried this on a vm, and on baremetal too, both failed to show data. I asked a friend fedoran to test too, downloading a new iso and he have confirmed my results.
Created attachment 1757982 [details]
History tab on the new plasma system monitor - blank
Created attachment 1757983 [details]
System settings showing that KSYSGUARDD still active on this build
Created attachment 1757984 [details]
Tried to search for the new KSystemStats service but none found
FEDORA-2021-4cb70a50e5 has been submitted as an update to Fedora 34. https://bodhi.fedoraproject.org/updates/FEDORA-2021-4cb70a50e5
Proposed as a Blocker for 34-final by Fedora user ngompa using the blocker tracking app because:
This violates the Fedora final release criterion for default application functionality: "All applications that can be launched using the standard graphical mechanism after a default installation [...] on the x86_64 architecture must start successfully and withstand a basic functionality test."
FEDORA-2021-4cb70a50e5 has been pushed to the Fedora 34 testing repository.
Soon you'll be able to install the update with the following command:
`sudo dnf upgrade --enablerepo=updates-testing --advisory=FEDORA-2021-4cb70a50e5`
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2021-4cb70a50e5
See also https://fedoraproject.org/wiki/QA:Updates_Testing for more information on how to test updates.
with ksysguard-5.21.1-2.fc34 there two ksysguard-libs is in repo ksysguard-libs-4.11.22-29.fc34 and ksysguard-libs-5.21.1-2.fc34
Since the update is already available (sans some dependency issues which need to be figured out), proposing as a Beta freeze exception.
+3 in https://pagure.io/fedora-qa/blocker-review/issue/262 , marking accepted.
Discussed during the 2021-03-01 blocker review meeting: 
The decision to classify this bug as a "RejectedBlocker (Final)" was made as the cited criterion is qualified on KDE to only cover a limited range of application types, and the system monitor is not one of them.
I'm not really inclined to pull an entire new release of Plasma just to fix this bug...
I can confirm, the System Monitor now shows data on the History tab.
Yes, with the updates, now system monitor works as expected. Hope the update reaches stable soon, so it can be part of the new ISOs.
FEDORA-2021-4cb70a50e5 has been pushed to the Fedora 34 stable repository.
If problem still persists, please make note of it in this bug report.