Spectator not drawing graphs

Both my PC and Android version of spectator doesn’t show graphs just overall summary in numbers like uptime, CPU load etc. So it must be by TO settings as both platforms connect but have the same issue.
I don’t know what I changed or what happened on TO, I just realized that graphs were shortly working just after download of 3.8 update but then immediately after reboot stopped working again.

Q: what files and settings are important for Spectator to work so I can look at them and diagnose the issue.

Thank you…

https://forum.test.turris.cz/t/spectator-a-updater-ng/4544

See https://gitlab.labs.nic.cz/turris/spectator and https://www.turris.cz/doc/cs/howto/spectator (in czech lng only).
It is not Turris package but supporting desktop and Android app for TO monitoring.

Thx but not related to my question. I know that problem but it’s something else.

Confirm, the same issue, both on Android and ArchLinux.