If the metric prefix or time unit of a derivative helper are changed the submission is saved but the unit stays the same.
A newly created derivative helper with unit_prefix: km, unit_time: h and source sensor for distance in meters yields the speed in km/h. Fine so far.
However, if I change either property it doesn’t take effect; the unit keeps showing as km/h. The config has been in fact saved to core.config_entries but it won’t matter, even if HA is restarted. If I delete the helper, purge statistics, restart HA and readd the helper with the same name, the unit still persists. The only workaround is adding the derivative with another name.
Where are these properties persisting, besides the database and the .storage folder? I’ve combed both, nuked all related data and still can’t figure how to make HA honor these unit changes.