I spent a lot of time trying to understand why Netdata wouldn't show my Raspberry Pi temperature while that was working without any problem on my Lenovo running Ubuntu.
Simple answer : you need to edit charts.d.conf but not the one in /etc/netdata but the one in /usr/lib/netdata/conf.d instead and add sensors=force.
If you're lazy, maybe echo sensors=force >> /usr/lib/netdata/conf.d/charts.d.conf can do.
It's as simple as that.
PS: $ sudo systemctl restart netdata afterwards.
