Full info would be cool… looks like you are using some derivative of debian. There is a chance you are missing a library or a command is different. This stuff is tested on the SNG7 which is an EL derivative. A lot of things do “just work” in debian because there is a strong presence of debian users in the community including those that use builds on the raspi.
I’ve seen a lot of my FreePBX15 and 16 distro systems show the same behavior. Some time later (hours or a day) after the system has been running a while the data will start to appear. System reboots will cause the “hour” stats to be blank again sometimes…
It always fixed itself after a period of time so I never really bothered complaining about it.
Thank you for the pointer: I have toggled the switch for the “Settings / Advanced Settings / Dashboard Module / Disable collection of system statistics” twice back to “No” and am getting now the statistics as depicted with: