Take a plasmoid for temperature control. 
Set to report: CPU, GPU, SSD, HDD temps. 
You will experience that:
At the boot time, SDD and HDD temperatures will be reported correctly. 
Then, when doing: refresh temp data 
manually, the data for CPU and GPU appears. 

I tried to fiddle with the refresh time settings, with slower or faster
refresh, size of character, size of plasmoid, orientation of plasmoid. It just
does not update these two automagicly. 
But I set this minor because, once you DO set it manually, it just works. 
With an uptime of hours, days or weeks does not matter as it seems. 

I join two images of the fact (mentioned with Mathias Homan also in the
opensuse (at) opensuse.org thread:
Annoying bug / incompatibility with temperature plasmoid in TW. (05.02.2019).