I created two Riemann Sum Integrations, one for each of my AC units (which are almost the same model)… One of them gets a complaint when I edit the Energy dashboard, but both of them seem to display fine on that dashboard.
According to tom_l, the source must be a power sensor, which both are… But one gets the correct energy class, and the other don’t (getting a histogram icon instead?? lol I didn’t set that manually, but interestingly the correct sensor shows a bookmark icon on the Helpers list, instead of the energy bolt)
EDIT: after a reboot to apply some unrelated settings, both sensors are now missing the device_class. At least the issue is consistent 
Besides going to YAML to manually customize that, any guess what might be going wrong?
Is it safe/permanent to set the device_class directly via DevTools > States?